feat "Mage slayer" and how it's played

[Entessa]

After reading this post (https://forums.giantitp.com/showsinglepost.php?p=25386102&postcount=5) I've been thinking a lot about the feat mage slayer. The link I just published has one user claiming that it's a weak feat, while for example, given that I play a paladin, here: https://forums.giantitp.com/showthread.php?375696-Good-is-Not-Nice-A-Paladin-s-Guide it is suggested to use it if you are sure your DM gonna put you against a lot of mages.

So, I've searched a bit around to understand what was the consensus about the feat itself - some disregard it ("weak") others don't ("great"). I've researched a bit around because I was actually unsure why there is this such a big chasm about the ideas and I think I found why some dislike the feat.

Quote from the feat (Source: Player's Handbook):

You have practiced techniques in melee combat against spellcasters, gaining the following benefits.

When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against that creature.
When you damage a creature that is concentrating on a spell, that creature has disadvantage on the saving throw it makes to maintain its concentration.
You have advantage on saving throws against spells cast by creatures within 5 feet of you.


I saw that the culprit for many people relies around the following words: "When a creature within 5 feet of you casts a spell".

Some DM seems to interpret them as "the mage has to finish casting the spell" and you can act later (see here: https://www.reddit.com/r/dndnext/comments/8jxmj9/mage_slayer_feat_worth_it_or_not/dz4qxwh/)

other DM read the rule as "you can act as soon as the mage start casting the spell, without waiting for it to end". --> My dm chose this.

My questions:
1) Does your DM interpret the rule in the first or the second way?
2) Given what my DM told me, would you say that Mage slayer is now serviceable, or is it still weak ?
3) Am I wrong or the feat is not that great because of the 5 feet distance? I should be able to realize who is a mage on every teamfight to use it.
4) Has your DM improved the feat distance by 2x or w/e?

[Lokishade]

If your DM doesn't allow you to hit when the caster begins to cast a spell, don't bother with this feat.

Mages have access to so many safe teleportation spells that they will never bother casting in your face. Allowing a hit before the mage bamfs away would save this feat from being mostly useless.

[Greywander]

Some DM seems to interpret them as "the mage has to finish casting the spell" and you can act later
I think this is a big part of the issue. The mage will just Misty Step or Dimension Door away, and there's nothing you can do to stop it. Not every mage will have a teleportation spell, though, but they can still mess you or an ally up before you get the chance to make that reaction attack.


other DM read the rule as "you can act as soon as the mage start casting the spell, without waiting for it to end". --> My dm chose this.
This is a lot better, as there's no way the mage can avoid the attack, even if they're teleporting. What would make it better is if they had to pass a concentration save against the damage or lose the spell they were casting, but that might be a hard sell to the DM. It doesn't hurt to ask, though. Though now I'm curious; what if they're casting a concentration spell? Do they not save against the damage, because they haven't actually cast the spell yet? Or do you have a chance to break their concentration before the spell even takes effect? Definitely follow up on that, because that could be a stealth nerf if it can't break concentration on whatever spell they're casting.


3) Am I wrong or the feat is not that great because of the 5 feet distance? I should be able to realize who is a mage on every teamfight to use it.
4) Has your DM improved the feat distance by 2x or w/e?
This is why I wish a lot of such features simply used your reach instead of a 5 foot distance. That said, I can certainly see it being intentional that it must be 5 feet, and not reach, for some of these types of features.

With the 5 foot distance, that means there's less benefit to using a reach weapon (you can still benefit while fighting anything that is not a mage, and using a reach weapon doesn't stop you from cuddling up to a mage). If you get PAM, consider a spear or quarterstaff with a shield, rather than a reach polearm.

[Samayu]

I don't think it's a hard sell to have it take effect before casting. For one thing, reactions are often used to take actions before triggering event. Also, it's not that overpowered, since doing damage isn't going to disrupt the spell unless you kill the caster. Or stunning strike him. OK, that's much more likely to happen.

Even if your GM doesn't agree, making the enemy use slots or actions to get away from you before you can reply is not the worst thing.

I took this feat once. The problem was not that it was ineffective in combat, it was that I only ran into one mage in the entire rest of the campaign. I was playing a monk so I was able to bypass the orc platoon, and get to the invisible mage.

So the problem for me is that though it is a lot of fun when you use it, you don't get to use it very often.

[Jerrykhor]

Mage Slayer sucks because its advertising itself as being the hard counter to casters, but its merely an annoyance to mages. I'm going to tell you something that will shock you: GWM/PAM is a better mage slayer than Mage Slayer. For GWM at least, once you reach 5ft of the mage, you better make him pay, and +10 damage helps with that. Why leave him alive for the next round? Now you might say, most Mages have Shield spell, but even with Shield they won't have more than 21 AC unless they are a Bladesinger. But lets say even if Mage Slayer was really good against mages, it would still be considered niche because GWM/PAM is good against everything else.

Mage Slayer is useless no matter your DM ruling. You usually start the encounter not within 5ft of the mage. They will get a few spells off before you could close the gap. Its something at low levels when they dont have many big spells. At higher levels, they will just Greater Invisibility or teleport away.

Sure, not every mage will have G. Invis or teleports. But the ones that don't will die even if you don't have Mage Slayer.

[Hytheter]

For the record, the reason Mage Slayer's reaction goes after the spell is that reactions always occur after the triggering event unless otherwise specified.

[Keravath]

It's just a matter of whether a DM chooses to play the feat "RAW" or to make it more usable.

The key issue is:
"When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against that creature."

Combined with the general rule on reactions.

Here is the rule from the DMG.

"ADJUDICATING REACTION TIMING
Typical combatants rely on the opportunity attack and the Ready action for most of their reactions in a fight. Various spells and features give a creature more reaction options, and sometimes the timing of a reaction can be difficult to adjudicate. Use this rule of thumb: follow whatever timing is specified in the reaction's description. For example, the opportunity attack and the shield spell are clear about the fact that they can interrupt their triggers. If a reaction has no timing specified, or the timing is unclear, the reaction occurs after its trigger finishes, as in the Ready action."

1) The trigger for the mage slayer feat is that a caster within 5' casts a spell.
2) The timing of mage slayer does not specify that it can interrupt the casting or otherwise change what has already happened like counterspell or shield which have explicit timing stated. If this is at all unclear then the reaction occurs after the trigger (so even if you want to interpret "casts a spell" as "begins to cast a spell" since it can easily be interpreted to mean when the spell is complete - the reaction will occur after the trigger if there is any argument about when it should occur since if the timing is unclear - the reaction happens after the trigger completes)
3) The wording of mage slayer doesn't have implied timing like "begins to cast a spell". It simply says "casts a spell".
4) The general rule from the DMG is that if the reaction does not include explicit timing then the reaction occurs when the trigger is complete.

In this case the trigger is "casts a spell", explicit timing is not indicated, so by the general rule from the DMG the reaction takes place after the trigger when the spell has been cast.

That is how it works RAW and I believe there are tweets out there indicating it is also RAI.

DMs might fairly frequently house rule this to allow an attack to interrupt the spell casting forcing a concentration check if hit and if failed the spell is not completed - but that is entirely a house rule from what I can tell. If your DM plays this way then the mage slayer feat is much better since it not only can be used to force concentration checks at disadvantage but can also possibly cause a spell to be lost by interrupting it. Of course the wizard could just disengage, move, cast misty step and likely be out of range of anything except a dash but it makes casting a spell while standing next to a creature with the mage slayer feat more risky.

[Entessa]

My dm has gone as far to:
1) Allow it to happen while casting
2) allow it to match the reach of my weapon. I wonder how much better it is now??

[Teaguethebean]

I allow it to get mages before they teleport. That is really the only change I had to make to make it a good enough pick for a rogue in a high level game I was running. She would close to melee range against an enemy mage and then often the mage would lose concentration with a DC16 or so check at disadvantage. Overall it isn't universally applicable, but in certain games it is pretty solid as a 2nd or 3rd feat.

[LudicSavant]

I'm going to tell you something that will shock you: GWM/PAM is a better mage slayer than Mage Slayer.

I've seen some recommenders of Mage Slayer who just go "oh, you want to slay mages? Well this feat is named Mage Slayer. That probably means it's extra good against mages, right?" I think the reasoning really is that simple for some internet posters.


For the record, the reason Mage Slayer's reaction goes after the spell is that reactions always occur after the triggering event unless otherwise specified.

Correct. The section on adjudicating reaction timing in the DMG spells it out.

[SociopathFriend]

My questions:
1) Does your DM interpret the rule in the first or the second way?
2) Given what my DM told me, would you say that Mage slayer is now serviceable, or is it still weak ?
3) Am I wrong or the feat is not that great because of the 5 feet distance? I should be able to realize who is a mage on every teamfight to use it.
4) Has your DM improved the feat distance by 2x or w/e?

1. My DMs have all gone with 'as the spell starts being cast' and not 'after the spell is cast'
2. It's incredibly serviceable IF you can get within 5 feet of the caster. I'm particularly fond of running it on Paladins because it practically ensures successful Saves.
3. and 4. The 5 feet rule alternatively exists to gimp all reach weapons or it's just the typical way of phrasing 'melee range'.

I give no shift to the first part of and neither of my DMs do either. I should not be punished for having a reach weapon.

[Entessa]

I should not be punished for having a reach weapon.
After reading this statement, I'm not totally sure what you were trying to say with your point 3 and 4.

[SociopathFriend]

After reading this statement, I'm not totally sure what you were trying to say with your point 3 and 4.

I'll try to explain better.

My two current DMs as well as every player at their respective tables have been fine with stuff like Green Flame Blade and Mage Slayer working with reach weapons.

I, personally, view the idea that you HAVE to be within "5 feet" as opposed to "in reach" is silly and is intended to make reach weapons less-attractive (nerfed, gimped, etc) to players.

It's not just Mage Slayer, I guess, is the context I wanted to add. It's reach weapons in general.

[Hytheter]

My dm has gone as far to:
1) Allow it to happen while casting
2) allow it to match the reach of my weapon. I wonder how much better it is now??

Honestly, it's probably still not worth a feat unless you're expecting to fight a lot of mages.

[animorte]

I would definitely say in order for it to be useful, it applies before the spell is finished. I say that for 2 reasons:

1. In the PHB, Reactions states - If the reaction interrupts another creature's turn, that creature can continue its turn right after the reaction. Which I think means as long as it isn't a concentration spell (which they would have to save to maintain), it's going to happen either way.

2. If I cast Eldtritch Blast in your face with Repelling Blast (and succeed), I will knock you at least 10 feet away (no save). Thus making the alternative (opportunity attack) completely worthless, and thus equally your feat.

Edit: If you want to use it, it's good. If you can close the distance in the first place, it's worth. Providing you're facing enough mages to not have other more broad options.

[J-H]

Thanks for posting this thread. I have incorporated the "can interrupt" capability into my houserules.

[ImproperJustice]

We don’t run it RAW and it’s useful, imagine that :)

[Ehcks]

For the record, the reason Mage Slayer's reaction goes after the spell is that reactions always occur after the triggering event unless otherwise specified.

But this is just an Attack of Opportunity, which is normally used when someone tries running away from you. You don't wait until they've finished their move. You attack as soon as you notice they're moving away from you. So of course Mage Slayer's AoO should be as soon as you notice they're casting a spell.

[Witty Username]

The primary issue for mage slayer is that it applies generally after spells have been cast. The Saves and reaction attacks only apply once the mage is within reach and it can break concentration but not obstruct the casting. this means alot of opening spells will frustrate use of the feat, such as say Web. This requires good initiative to go first, decent mobility to close the gap, and critically both of these while fighting a mage.
Essentially, Mage Slayer requires alot of effort to work as intended which is bad for an option that is already situational.

[Hytheter]

But this is just an Attack of Opportunity, which is normally used when someone tries running away from you. You don't wait until they've finished their move. You attack as soon as you notice they're moving away from you. So of course Mage Slayer's AoO should be as soon as you notice they're casting a spell.

A) Mage Slayer is NOT an opportunity attack. Not every reaction attack counts as an opportunity attack. The Mage Slayer feat doesn't say anything about being an opportunity attack, therefore it isn't. Contrast with Polearm Master, whose reaction is specified to be an opportunity attack.

B) The rules for Opportunity Attacks specify that they go before the movement takes place. "The attack interrupts the provoking creature's movement, occurring right before the creature leaves your reach." This specific rule overrides the general rule of reactions going after their trigger, but Mage Slayer has no such provision.

[LudicSavant]

But this is just an Attack of Opportunity, which is normally used when someone tries running away from you. You don't wait until they've finished their move. You attack as soon as you notice they're moving away from you. So of course Mage Slayer's AoO should be as soon as you notice they're casting a spell.

Mage Slayer is not an Opportunity Attack.

[Eldariel]

Mage Slayer takes your reaction to attack once. It's basically just an extremely restricted opportunity attack option that doesn't even disrupt enemy spellcasting. If attacking while casting could negate the spell, it could be somewhat interesting against mages but as it stands? You just want more attacks and more damage to kill the mage faster. And PAM/GWM give a bigger improvement in attacks and damage even against mages.

The bonus to breaking Concentration is the best ability to the spell but frankly, for any individual roll it's only ~25% or less to matter anyways. Means you need to hit Concentrating people a lot for it to give you much mileage. And the last ability? Casters can literally just walk away from you and cast as per normal, or cast a spell that doesn't offer a save, or whatever.


It's too situational to be a feat, even if you only face casters all game. If you had ways to stop them from leaving your side and disrupt spells, it could potentially be somewhat interesting.

[tokek]

It is pretty normal for a reaction to be triggered before the triggering action is completed. Counterspell is the most obvious example.

With that trigger this is a pretty decent feat. If you also permit the DMG combat options the martial character could try to disarm the mage of their component/focus with the reaction attack, which honestly feels like a damn obvious thing that should happen unless the mage can get by without any material components.

Played like this I feel the feat would live up to its name without being busted in any way.

[Rynjin]

Yeah, this Feat seems bad no matter how you slice it. 5e's mechanics are just way too friendly towards casters in situations they'd normally be disadvantaged. While magic is weaker in many ways than previous editions, it's also harder to DO anything about it as a non-caster.

In previous editions you could ready an attack to whack the caster when they started casting, and had a solid chance at interrupting. This was especially good with bows. Getting hit while casting at mid to high levels forced a DC of "better hope you roll a 20, chump" Concentration check to succeed on casting the spell, so it was a solid option. And there was always the chance that even if you didn't do that, the caster in melee could flub their Casting Defensively check and lose the spell, or not try it at all and get bonked; these were much less likely, but could happen even with zero Feat investment.

The design of this Feat is very confusing because as others have stated, even if you houserule it to trigger before the spell (which can be achieved by just making the text "when a creature BEGINS TO CAST A SPELL")...it still sucks. It's just a smidge of extra damage but now you can't use your Reaction for anything else if you might need to.

[Glorthindel]

It doesn't matter how you adjudicate it, Mage Slayer still sucks. I joked in last nights session that if my (now 9th level) Paladin had the Mage Slayer feat, a fight at the end of the last session would have been literally the first time it would have activated (and even to have been in that position required me to be using a Potion of Flying).

Mage Slayer (and Mounted Combatant and Charger) should just be baseline abilities for melee characters, because they absolutely aren't worth a Feat.

[LordNibbler]

The bonus to breaking Concentration is the best ability to the spell but frankly, for any individual roll it's only ~25% or less to matter anyways. Means you need to hit Concentrating people a lot for it to give you much mileage. And the last ability? Casters can literally just walk away from you and cast as per normal, or cast a spell that doesn't offer a save, or whatever.

This is THE reason to take this feat. Spells that require concentration can be encounter-changing. Heat Metal slowly broiling your Hit Point Sponge…I mean…Fighter in his full plate? Is everyone in your party Slowed? Is your best striker Held? Breaking these effects can save your party. This is what your smiting Paladin is built for. Make that caster concentrate with disadvantage on the nova attack.

[Silly Name]

This is THE reason to take this feat. Spells that require concentration can be encounter-changing. Heat Metal slowly broiling your Hit Point Sponge…I mean…Fighter in his full plate? Is everyone in your party Slowed? Is your best striker Held? Breaking these effects can save your party. This is what your smiting Paladin is built for. Make that caster concentrate with disadvantage on the nova attack.

But this is also the issue with Mage Slayer - it competes with other, better options to help you make an enemy break Concentration. Polearm Master and GWM are far more efficient at making mages break Concentratrion - heck, even Charger can help more -, and it's not like Paladins have trouble dishing out high DC for Concentration checks in the first place. Imposing Disadvantage is nice, but that's so far down the line when compared to realising the rest of your build, it gets shunted away.

There's also the issue that Mage Slayer has a very specific application, whereas stuff like Charger, PAM and GWM is "always on". Unless you're 100% sure you're going to be facing a lot of casters, those feats are way better than Mage Slayer. This same issue is shared by other feats that are nice on paper, but become worthless if the campaign isn't the right environment for them: Dungeon Delver is nice if you're spending a lot of time in dungeons with secret passages and traps - but it's absolutely useless if you don't.

[tokek]

It doesn't matter how you adjudicate it, Mage Slayer still sucks. I joked in last nights session that if my (now 9th level) Paladin had the Mage Slayer feat, a fight at the end of the last session would have been literally the first time it would have activated (and even to have been in that position required me to be using a Potion of Flying).

Mage Slayer (and Mounted Combatant and Charger) should just be baseline abilities for melee characters, because they absolutely aren't worth a Feat.

I sort of agree.

I think those feats should be tied into features of appropriate backgrounds.

Knight - mounted combatant
Soldier - mage slayer
I'm not so sure on Charger - although it does feel sort of perfect for Uthgardt Tribe Member

I realise some people seem to hate putting feats with backgrounds but I rather like it.

[Tanarii]

It's not really relevant if it goes before or after the spell is cast. The number of times you're going to be facing a caster, adjacent, and that timing makes a difference is vanishingly small compared to the already small chances of the first two happening.

Now if it prevented a spell from being cast, it might be worth it for those few occasions the first two things happened. But neither reading does that.

[tokek]

It's not really relevant if it goes before or after the spell is cast. The number of times you're going to be facing a caster, adjacent, and that timing makes a difference is vanishingly small compared to the already small chances of the first two happening.

Now if it prevented a spell from being cast, it might be worth it for those few occasions the first two things happened. But neither reading does that.

For concentration spells it would matter. Concentration starts the moment you begin casting so any damage would force a concentration check at disadvantage or the spell fails before it even takes effect.

I agree its situational but at least it would be good when it worked.

(Or at least that is my understanding from the fact that you drop concentration the moment you begin casting a new concentration spell)

[Tanarii]

Nothing says concentration drops when you start casting another spell with concentration. It's entirely possible to read the concentration mechanic as it drops when you finish casting another concentration spell. It just says "when you cast". That can be read either way.

Regardless, if a DM happened to rule that concentration kicks in when you start casting a concentration spell, and house rules that it interrupts casting, the feat is minorly more useful.

[RSP]

I’d say something like Skill Expert (taking Expertise - and Proficiency - in Athletics) would be much better at actually combating casters (via Grappling), as well as other situations, and you get a +1 ASI to boot.

MS is a better (better relative to itself, that is) Feat if the attack occurs before the spell is cast but is a) a lot more niche than opportunities to use Athletics (Grapples, Shoves or otherwise), b) casters teleporting escapes MS and Grapples both, c) non-teleporting casters can eat an OA to just leave the range of MS, whereas it takes their Action to attempt that with Grapples (and still eat the OA).

I’ve been thinking of an anti-caster build lately and I’d say a Melee-built DS Sorc w/ Expertise Athletics, Misty Step, Silence, and Quicken and Subtle Spell Metamagic, is up there with a Monk with Expertise Athletics (movement bonus + Stunning Strike).

The DS can Silence and Grapple, basically completely shutting down and locking down casters. Misty Step and Subtle make them able to get to back rows and still function within the Silent radius at full strength.

If the enemy caster uses their Action to escape, then moves, you get an OA, then just MS to them again, re-grapple and drag them back to the Silence area.

It’s a lot more effective than Mage Slayer at slaying casters (as is the Monk level 5+). Granted, the build is more than just a Feat, but it’s much more functional than trying to build a “mage slayer” with the Feat.

Note: Mage Slayer on said Monk is probably the best use of the Mage Slayer feat (IMHO), however, Monks are notoriously Feat starved so adding that to the build isn’t easily done - I’d rather up Dex or Wis.

[Spiritchaser]

This just came up in another thread…

I houserule that the reaction attack occurs before the spell resolves and if the attack hits, it forces a concentration check or the spell fails.

This hasn’t come up much (it’s pretty situational) but when it does happen it’s really quite strong, especially with the disadvantage on that check.

I generally don’t like build options that are seldom useful but which are exceptional when they apply, but they’re better that trap feats.

To be honest though, I just don’t have enough play test time on this one, It just hasn’t come up enough.

[tokek]

Nothing says concentration drops when you start casting another spell with concentration. It's entirely possible to read the concentration mechanic as it drops when you finish casting another concentration spell. It just says "when you cast". That can be read either way.

Regardless, if a DM happened to rule that concentration kicks in when you start casting a concentration spell, and house rules that it interrupts casting, the feat is minorly more useful.

Just one of those JC tweets as a source for that. So disregard if you typically disregard the tweets.

https://twitter.com/jeremyecrawford/status/1083443480825741312?lang=en

From the wording "You lose concentration on a spell if you cast another spell that requires concentration."

Its the same wording issue as the feat. When does "cast a spell" start? If it starts when you start casting the spell then clearly that causes the previous concentration to end at that point.

If you rule "cast a spell" to only happen when the spell is completed and takes effect then none of the above applies, either to the feat or the concentration check. The only actual clear ruling was on ritual spells (yes you concentrate from the moment you start casting one) so for spells that take one action to cast we only really have that tweet to clarify the intent of "if you cast another spell"

[Keravath]

But this is just an Attack of Opportunity, which is normally used when someone tries running away from you. You don't wait until they've finished their move. You attack as soon as you notice they're moving away from you. So of course Mage Slayer's AoO should be as soon as you notice they're casting a spell.

I'll repost the quote from the DMG since this is the source of all the discussion. RAW is pretty clear.

"ADJUDICATING REACTION TIMING
Typical combatants rely on the opportunity attack and the Ready action for most of their reactions in a fight. Various spells and features give a creature more reaction options, and sometimes the timing of a reaction can be difficult to adjudicate. Use this rule of thumb: follow whatever timing is specified in the reaction's description. For example, the opportunity attack and the shield spell are clear about the fact that they can interrupt their triggers. If a reaction has no timing specified, or the timing is unclear, the reaction occurs after its trigger finishes, as in the Ready action."

The attack provided by Mage Slayer is "When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against that creature." .. it is not an opportunity attack. As the rule cited above states, opportunity attacks and the shield spell have separate specified timing. The attack from Mage Slayer does not.

The discussion here covers both the house rules that some folks use to make it a better feat and the actual rules as written that would prohibit the attack from Mage Slayer from interrupting a spell casting.

[Entessa]

I've decided to switch the feat. My DM allows it and the only things he is allowing to happen is for the attack to happen while the enemy is casting the spell. Otherwise, no more stuff.

I have asked for the following to be added to the feat, all the following things had to be allowed simultaneously to make me not change mage slayer:
1) If I attack a person casting a spell, the attack goes through before the spell. ALLOWED
2) all spells are treated as concentration spells if someone has a mage slayer is attacking you. Denied
3) "When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against that creature." --> changed to: When a creature within "your weapon reach" casts a spell - Denied
4) You have advantage on saving throws against spells cast by creatures within 5 feet of you. --> changed to within 20 feet of you. Denied.

Basically my issue with the feat is that the only thing allowing you is to attack mage once, but what's gonna happen is the following:
1) You won't go in the face of the mage, because you are going to get ganked by his bodyguard.
2) The mage, if the DM doesn't nerf them, the second you are in front of him is going to cast Misty step or invisibiltiy stuff. So you attack him once then you are ****ed.
3) There is no concentration forced on spell when you attack them, so the spell always succeeds.
4) you are supposed to always be on his face, but you gain nothing by doing so - well you gain a TS advantage and the possibility to hit him once, only to gain: a) getting ganked by his bodyguards/companions b) him escaping and laughing at you - maybe putting himself 6 feet away and *bam* your advantage is gone.

[SociopathFriend]

I have asked for the following to be added to the feat, all the following things had to be allowed simultaneously to make me not change mage slayer:
1) If I attack a person casting a spell, the attack goes through before the spell. ALLOWED
2) all spells are treated as concentration spells if someone has a mage slayer is attacking you. Denied
3) "When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against that creature." --> changed to: When a creature within "your weapon reach" casts a spell - Denied
4) You have advantage on saving throws against spells cast by creatures within 5 feet of you. --> changed to within 20 feet of you. Denied.


I have to agree with the DMs assessment for all of these but point 3.

Mage Slayer is primarily intended for offense- not defense. That means you need to get close to benefit from it. If you want help making saves at longer range then that's what Bards, Clerics, and Paladins are for.

Also turning any spell into a Concentration one for the price of one feat might be just a biiiiit excessive. Mage Slayer isn't supposed to turn any contact with a mage into a one-sided affair where every single action they take is crippled.

[Entessa]

I have to agree with the DMs assessment for all of these but point 3.
Mage Slayer is primarily intended for offense- not defense. That means you need to get close to benefit from it. If you want help making saves at longer range then that's what Bards, Clerics, and Paladins are for.
Also turning any spell into a Concentration one for the price of one feat might be just a biiiiit excessive. Mage Slayer isn't supposed to turn any contact with a mage into a one-sided affair where every single action they take is crippled.
I don’t agree with you and my DM and that’s why I simply moved away from the feat mage slayer. I do not regret it and I feel like I’ve chosen the best course of action given what’s the feat about. Currently if there is a tier of all the feats you can get, I feel like the Mage slayer feat is a TIER “Avoid at all cost”.
I wanted to publish my thoughts into the paladin handbook published in this very same website but it’s not possible, so I will just share what I think here.

Mage slayer description:

When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against that creature.
You have advantage on saving throws against spells cast by creatures within 5 feet of you.
When you damage a creature that is concentrating on a spell, that creature has disadvantage on the saving throw it makes to maintain its concentration.


I’ve been playing D&D 3.5 for 15 years and D&D 5 for a few months and you can bet on it that I’ve never seen the things mentioned in the mage slayer feat happen once in my sessions.

I have never seen, in 15 years, a mage casting in front of a fighter his own spells. IF we are referring to a mage worth his weight.
Ironically, the feat itself works in a way that this effect by the feat is perfectly avoidable: the spell is supposed to happen before the attack, so if you take it by RAW the feat is completely useless. Completely trash tier, not even worth putting the ink on the guide to make it known.

Even if you don’t take it raw, and the player can attack you before the spell ends, there is an issue: As a player, feats are supposed to improve the way I play the character by providing new possibilities and not forcing you into a suicidal playstyle. Let’s imagine two sceneries:
1) A mage with a party. I see a mage and what I’m supposed to do to use my feat is to charge him to reach him so I can use the advantages provided by the bonus. I have never seen a mage alone, so you could bet that by doing so I would isolate myself from the party and I would get killed by 4-5 people ganking on me all together.

2) A mage alone. I go on him , but even if I get my attack of opportunity on the guy, what did I achieve? Really, all the feat provides is just one attack of opportunity if you are good enough to stay in front of him.

But if a mage plays decently, if any DM plays a mage decently, the second you are on his face, he could cast a lot of spells and get out without issues. That’s also if he is a “mere” human.
You are totally right, mage slayer is tailored for the offensive, in the sense that it helps DM kill your own character by forcing the player into unnatural playstyles just to get an attack of opportunity (or the meager benefits of the feats) because they have to be in the face of the mage.

Mage slayer in its current iteration should be changed into “player slayer” or “mage hater”. You cannot slay any mage with that talent, you could do better with any other decent talent.

The ts is useless as well (all the mage has to do is just go far from you and no more ts) and the concentration is useless as well (giving myself +2 to STR can achieve that much and maybe better too)?

TLDR: don’t take mage slayer. Either put +2 into STR if you are a a paladin or go for other decent talents; suggestions:
resilient: Con
Polearm master

[Entessa]

It's just a matter of whether a DM chooses to play the feat "RAW" or to make it more usable.

The key issue is:
"When a creature within 5 feet of you casts a spell, you can use your reaction to make a melee weapon attack against that creature."

Combined with the general rule on reactions.

Here is the rule from the DMG.

"ADJUDICATING REACTION TIMING
Typical combatants rely on the opportunity attack and the Ready action for most of their reactions in a fight. Various spells and features give a creature more reaction options, and sometimes the timing of a reaction can be difficult to adjudicate. Use this rule of thumb: follow whatever timing is specified in the reaction's description. For example, the opportunity attack and the shield spell are clear about the fact that they can interrupt their triggers. If a reaction has no timing specified, or the timing is unclear, the reaction occurs after its trigger finishes, as in the Ready action."

1) The trigger for the mage slayer feat is that a caster within 5' casts a spell.
2) The timing of mage slayer does not specify that it can interrupt the casting or otherwise change what has already happened like counterspell or shield which have explicit timing stated. If this is at all unclear then the reaction occurs after the trigger (so even if you want to interpret "casts a spell" as "begins to cast a spell" since it can easily be interpreted to mean when the spell is complete - the reaction will occur after the trigger if there is any argument about when it should occur since if the timing is unclear - the reaction happens after the trigger completes)
3) The wording of mage slayer doesn't have implied timing like "begins to cast a spell". It simply says "casts a spell".
4) The general rule from the DMG is that if the reaction does not include explicit timing then the reaction occurs when the trigger is complete.

In this case the trigger is "casts a spell", explicit timing is not indicated, so by the general rule from the DMG the reaction takes place after the trigger when the spell has been cast.

That is how it works RAW and I believe there are tweets out there indicating it is also RAI.

DMs might fairly frequently house rule this to allow an attack to interrupt the spell casting forcing a concentration check if hit and if failed the spell is not completed - but that is entirely a house rule from what I can tell. If your DM plays this way then the mage slayer feat is much better since it not only can be used to force concentration checks at disadvantage but can also possibly cause a spell to be lost by interrupting it. Of course the wizard could just disengage, move, cast misty step and likely be out of range of anything except a dash but it makes casting a spell while standing next to a creature with the mage slayer feat more risky.

I really think Jeremy Crawford got this one wrong. IMHO, the Mage Slayer feat needs clarification that it (a) works against Shocking Grasp (which is a cantrip and completely negates the point of the Mage Slayer feat) and (b) works prior to Misty Step's teleportation.

First, I believe the rule, as written and using grammatical rules is clear that the reaction in Mage Slayer can be taken in reaction to a spell in the process of casting. The text clearly states: "When a creature within 5 feet of you CASTS a spell, you can use your reaction to make a melee weapon attack against that creature." (emphasis is mine) Casts in the English language is always used in the present tense, i.e., signifying that it is simultaneous to an event occurring. The trigger, in this case, would be as the creature is in the process of casting a spell, similar to that of Counterspell. That trigger resolves immediately and before the spell is completely resolved.

The rules in the PHB for reactions support this interpretation. "A reaction is an instant response to a trigger of some kind, which can occur on your turn or on someone else's." The key word in the above is "instant", further supporting the immediacy of the reaction. The rule even supports the interruption of a turn: "If the reaction interrupts another creature's turn, that creature can continue its turn right after the reaction."

This is not in conflict with the DMG's rules regarding the timing of the reaction found on page 252 which states that "if a reaction has no timing specified, or the timing is unclear, the reaction occurs after its trigger finishes". As Jeremy Crawford noted in his discussions on twitter regarding the same rule, the PH and DMG rely on everyday English. As I noted above, the Mage Slayer feat explicitly states that the trigger occurs when a creature within 5 ft "casts" a spell. Because the word "casts" is used specifically, based on English grammatical rules, it must be a presently occurring--i.e., the trigger would resolve concurrently. The same reasoning is applied to Counterspell where the trigger is when you see a creature "casting a spell"; another present tense version of the word "cast".

For clarity, this does not conflict with Xanathar's clarification that "If you’re unsure when a reaction occurs in relation to its trigger, here’s the rule: the reaction happens after its trigger completes, unless the description of the reaction explicitly says otherwise" for the exact same reason as above. The trigger of the feat is explicitly a present tense trigger.

The practical implications of the above would be as follows: when a creature attempts to Misty Step away, the Mage Slayer feat would allow a player to take the melee attack. That attack would resolve and the misty step would also resolve unless there was some other mechanic that prevented it from resolving (which, I believe is not currently in the game). Notably, this would not trigger any effect from the Sentinel feat. For any other spells, since this attack occurring simultaneous to casting of the spell, the creature would likely not have concentration on the new spell yet and would not trigger the second part of the Mage Slayer feat, i.e., the concentration check, unless there was an ongoing spell with concentration.

For Shocking Grasp it would work the same way. Shocking Grasp would prevent normal players from taking attacks of opportunity from the retreating spellcaster, but the Mage Slayer would allow the player to immediately use the reaction in response to the cantrip to make the counterattack. If it were otherwise, the feat Mage Slayer would be relatively pointless.

[Tanarii]

First, I believe the rule, as written and using grammatical rules is clear that the reaction in Mage Slayer can be taken in reaction to a spell in the process of casting. The text clearly states: "When a creature within 5 feet of you CASTS a spell, you can use your reaction to make a melee weapon attack against that creature." (emphasis is mine) Casts in the English language is always used in the present tense, i.e., signifying that it is simultaneous to an event occurring. The trigger, in this case, would be as the creature is in the process of casting a spell, similar to that of Counterspell. That trigger resolves immediately and before the spell is completely resolved.

Casts a spell is an atomic event for a reaction trigger perspective. And most other rules perspective. CASTS doesn't mean "starts casting but before finishes casting". Also in English it is ambiguously present or past.

Counterspell is a case of specific vs general, as it specifically tries to "interrupt a creature in the process of casting a spell". Mage Slayer doesn't contain any language similar to this, so it's bound by the general rule of reaction occurs after trigger.

In short, caster casts a spell, trigger of "casts a spell" finishes, mage slayer reaction attack happens.

[Sorinth]

Casts a spell is an atomic event for a reaction trigger perspective. And most other rules perspective. CASTS doesn't mean "starts casting but before finishes casting". Also in English it is ambiguously present or past.

Counterspell is a case of specific vs general, as it specifically tries to "interrupt a creature in the process of casting a spell". Mage Slayer doesn't contain any language similar to this, so it's bound by the general rule of reaction occurs after trigger.

In short, caster casts a spell, trigger of "casts a spell" finishes, mage slayer reaction attack happens.

Does it say casting is an atomic event anywhere in the rules or is that an assumption on your part?

I do agree casts can be ambiguous about present or past tense which means RAW it could be either. Since it can be either why not go with the reading that makes it at least semi-useful?

It could easily be read to be
Caster finishes casting spell
Mage slayer gets attack
Spell effect occurs

Especially since many spells describe time passing as part of the spell description. So why couldn't the mage slayer attack happen after Misty Step is cast while the caster is briefly surrounded by silvery mist?

[Angelalex242]

Cause he's not there anymore. He's poofed, and your sword passes through empty air, rendering you looking like the chumpiest chump that ever chumped.