Arcane Trickster Mage Slayer

[ChaseC311]

Years ago, I made a post asking about help building the perfect antimage, and thanks to my fellow forum users we created a Paladin Sorcerer Warlock Multiclass!

Needless to say the tripleclass character is now infamous in my friend group because he was a menace with burst damage. Now I want to revisit the idea of an antimage without tripleclassing. Overall I was thinking an arcane trickster perhaps? With their flavor being that they're an arcane hacker thats adept at infiltrating the spellweave (Basically Sombra from Overwatch but with a magic wand lmao). I was also thinking the mage slayer feat? Would this work for the build I'm going for? What kind of race/additional feats/spells could help in shutting down mages (beyond counterspell and dispel magic. Those two are easy picks of course)? Like always, any and all feedback is appreciated ^-^

[RogueJK]

For a build focused around Mage Slaying, you're going to want a few things:
A) Mobility, to close the distance with a Mage
B) The ability to prevent an enemy mage from moving away from you
C) Counterspell, to shut down the caster's big spells

The Mage Slayer feat is thematically appropriate but not great, and Mage Slayer's attack doesn't actually interrupt the spell they're attempting to cast, plus you only have one Reaction so on each turn you'd have to choose between Mage Slayer's damage or Counterspell's spell shut down.

A Rogue, even an Arcane Trickster, gets you A, but not B, or C (until at least Level 14).

Instead, I'd focus on some flavor of full caster counterspeller-gish instead, such as a Bladesinger, Abjuration Wizard, or Lore Bard. A Paladin 2/Lore Bard X makes for a great anti-caster gish, but since you've already played a Paladin multiclass, try a Hexblade 1/Lore Bard X, which makes for a dandy gishy counterspeller. Something like this:

Tabaxi or Dhampir Hexblade 1/Lore Bard 6+
STR 8
DEX 14
CON 15+1
INT 8
WIS 10
CHA 15+2
ASIs: Warcaster, Mage Slayer (maybe), Fey Touched (18 CHA)
Magical Secrets at Bard 6: Counterspell, Spirit Guardians

Your goal is to first attempt to shut the caster down at range with a spell like Blindness or Silence, and then close with the enemy caster using your good speed and mobility, snuggle up next to them, and beat on them with Booming Blade attacks until they go down. You've got half Proficiency added to Initiative from Jack of All Trades, plus you can grab Gift of Alacrity from Fey Touched, so you can hopefully take your first turn before the enemy caster can act.

You've got half Proficiency Bonus added to your Counterspell checks thanks to Jack of All Trades, and you can use Booming Blade Warcaster OAs to punish the enemy from trying to move away from you. Spirit Guardians not only slows them down so that they're unlikely to get more than 15' feet away on their turn, but it also causes them to take additional damage every round to further mess with Concentration.

From Hexblade 1/Lore Bard 6, consider going for something like Lore Bard 6/Hexblade 5, to get even more Counterspell slots that recharge on a short rest, plus Extra Attack from Pact of the Blade. From there, decide if you want higher level Warlock spells, or higher level Bard spells.


Hexbladelock 5 -> Whispers Bard 5 is another alternative build option, getting you Counterspell online 2 levels sooner plus Extra Attack from Thirsting Blade, and eventually 5x Counterspell slots at a time plus +3d6 Psychic Blades damage on demand, plus Jack of All Trades for Counterspell checks. But no Spirit Guardians available there.

[Kane0]

You could try a Monster Slayer Ranger, especially now that Tashas is out to make Rangers more fun in general. You can of course swap over to a dip in Rogue and/or fighter whenever you want on top.
The Mage Slayer feat is thematic but not actually that great. Maybe try Mobility, Fey Touched or Lucky instead.

Unless of course, homebrew is on the table...

[RogueJK]

Monks also make solid martial Mage Slayers. They've got the mobility to get to the casters quickly, and Stunning Strike is a great way to totally shut down a caster. Eventually, Diamond Soul makes it very hard to land spell effects on them.

Shadow Monks specifically get even further mobility from their BA teleport, plus can cast Silence for 2 Ki.

[Jerrykhor]

Honestly, Mage Slayer feat is a trap. Its really a lot worse than it looks, you're better off taking Tough to be able to absord more spell damage, or taking a damage feat like PAM to kill mages faster, which ironically makes it a better mage slayer than Mage Slayer.

[Bosh]

Honestly, Mage Slayer feat is a trap. Its really a lot worse than it looks, you're better off taking Tough to be able to absord more spell damage, or taking a damage feat like PAM to kill mages faster, which ironically makes it a better mage slayer than Mage Slayer.

Well the advantage on saving throws is very nice...if that sort of thing crops up a lot. Which I've NEVER seen in any campaign I've played in or run. But in a very specific sort of campaign it could be nice I guess...

[Jerrykhor]

Well the advantage on saving throws is very nice...if that sort of thing crops up a lot. Which I've NEVER seen in any campaign I've played in or run. But in a very specific sort of campaign it could be nice I guess...

That's what i mean, it will not come up. I don't think OP is taking Mage Slayer to get advantage on saves vs a novice mage who cast Burning Hands in your face. You'd wipe the floor with that spell caster even without a proper anti-mage build.

Mage Slayer does nothing against any competent spell caster. To be an anti-mage, you are not expected to one-round a caster, that is not the goal. The most important thing is to be the biggest threat to the spell caster, and to do that you have to apply a lot of pressure on them. Mage Slayer does absolutely nothing to help with that. You almost never start within kissing range of the caster, and even if you do, feats like Alert is better for winning initiative.

The best anti-mage build is Ancients Paladin with Mounted Combatant feat, on a warhorse (or Gryphon once your have the Greater version). Also take GWM, PAM, or if you are a 1 handed build, Shield Master. Resilient/Warcaster is a plus, but you can live without them. Bless+Aura will keep you safe. You might notice this build doesn't have Counterspell, its fine. You have teammates who can do that. Even if they don't, it doesn't matter, the enemy mage will soon realise you are the biggest threat and focus on you. But they cannot stop you, with your big plus to saves, magic resistance, fast movement and misty step. Yes, you can teleport your mount with you too.

[Gignere]

I’d say anything with a way to either block the caster’s LoS or silence the caster, having access to a teleport, and combined with the sentinel feat would make for a very effective mage slayer.

Given this combination an arcane trickster can work but you’ll likely need a race that can provide you with a teleport early on to be super effective. Potentially a dip into fighter to get access to blindfighting or at least an ASI to get that feat.

Strategy is to teleport/get next to the caster, drop a fog cloud / darkness / silence. If the caster tries to disengage, you sentinel him and get him stuck in the sight blocker or silence.

[Corran]

Yeah, as far as mage slayers go, you could do better than going for a rogue.

That said, here is what you can do well against casters.

1) Stealth
Casters are fragile. So if you can get close to them and attack them before they get a chance to act (barring contingency or simlar in nature abilities that step up from the usual reaction spells/ spell like abilities), you improve your chance of winning. As an arcane trickster you most likely dont have enough of a strong punch to do this on your own, so you'll most likely need at least one or two allies with at least some (ranged) nova potential. Which means that stealth includes allies. But at least you have the tools to build up yours and help towards that approach being successful if at all possible.

2) First hit
The first hit must be strong. Ideally you want to take out or at least neutralize the enemy caster before they have a chance to act. This translates to one of three things: a) strong melee attack combined with mobility, b) strong ranged attack, or c) something else. You ranged and melee attacks do pretty much the same damage since the bulk of the damage comes from sneak attack. It's decent damage normaly, but it's mediocre when the goal is to take down a caster on your own in one turn. So let's examine option c. Your option C is making the most of your spellcasting along with your magical ambush ability. With the right spell, this option will have a higher ceiling than if you were trying to pile the damage on your own. What's the right spell? There are some optons here. Hold person can be good if the caster is humanoid, perhaps a bit of an overkill or even a bit lackluster if no allies can apporach fast for the kill. Banishment can be excellent if the caster does not have legendary resistances, though you are not getting it early (or at all), and even if/when you do, you'll miss on its upcasting potential. Slow can work against a medium armor of casters (ideally gish types; eg gith) if they dont have a great destructive spell potential (eg lone archmage) cause in this case it becomes too risky. Probably a few more that dont come to mind. All in all, you've got some options here. They are decent, even if some of them a bit situational. The real problem will be opportunity cost (being a 1/3 caster is part of that), as there are a lot of spells that can be useful for tricksters, and tailoring your non-specific school picks to any ones of the above is limiting you in many ways that may or may not be obvious at first glance. But it's (ie your spellcasting) is an option, and in some cases (eg because of enemy vulnerabilities, positioing, generally because of encounter set up) it will be your best option, so I wanted to mention it.

Obviously, you can profit from magical ambush mid combat, since the requirement is to be hidden, and you have the action economy to attempt it at no big cost when the opportunity exists, but generally speaking you dont want to have casters linger about for too long, hence why I went with first strike in the beginning.

3) Counterspell
Late access to the spell, but more than that, having to dedicate a non school specific pick and having only so many slots to back it up, are not doing you any favours here. But, what you have going for you, is that unlike most counterspellers out there you have both incentive (more on that later) and the opportunity (cunning action) to be in a better position to counterspell than them. That means, to be within 60 feet as required by the spell. But also, you can try to be hidden too. Being hidden when you counterspell (ask your DM if casting counterspell will tend to break stealth in your game, as it has a somatic component) means that the enemy casters does not get a chance to counter your counterspell. So yeah, high opportunity cost on it, both in terms of picks and slots, but at the very least if you have it and you can spare the slot, you can be more effective than the average counterspell if you can exploit your mobility and stealth.

4) Sight
Most (well, if not most, then quite a lot of) spells require the caster to see you in order to target you. So having a way to become unseen can be incredibly useful against casters. I say "can be", cause personal survivability can only take you so far, as the caster might try to target someone else instead in this case. If they bother to target any PC at all; they can hurt you without targeting you directly, eg by targeting an area, or by summoning stuff, etc. Nevertheless, it's certainly not bad if you have ways to become unseen. Cunning action can help here a lot (eg dashing to get behind cover or to get out of range, or simply hiding), but you've got some spell support. Greater invisibility is particularly great for this (generally it's excellent on rogues), assuming you level up enough to get it or assuming that an ally can provide it. The skulker feat can also be excellent for rogues (maybe a little less so on arcane tricksters who can rely on spells too compared to other rogues; still good though), as it can allow you to attempt to hide in some occasions when you would otherwise not be able to. And then there is obscurement, which you can provide by relying on spells like fog cloud, silent/major image or darkness. But before delving into those, let's go back a bit.

While it can be very beneficial if you make yourself untargettable to cetain spells by becoming unseen, it logically follows that it will be preferable (assuming allies) if you can focus on denying sight to the caster in general, so that not only you will be untargettable by certain spells, but your allies as well. Enter the aforementioned fog cloud, darkness and silent/major image. Let's also introduce the blindess (/deafness) spell here, and tie it with what I said earlier in first strike regarding magical ambush. Maybe bestow curse can be of use if you can replicate blindness while adding another god debuff on top of it (think of something and ask your DM). Blindness and similar debuffs are intuitive in their use. The area obscurement spells though require more of a specific approach. I wont go into details about how silent/major image works and interacts with stuff, cause I could be mistaken (until relatively recently I was using it in a way I now think I shouldn't have, at least by RAW). The extra thing that you have to consider for these area sight-denial spells is positioning. Before going into that, let me just mention that (the immobile) fog cloud has the benefit that it's not pierced by true seeing or true sight.

5) Positioning
Either you want to stay out of the range of your enemy's worst spells (find out what they are capable of) and maybe jump in and out of counterspelling range if you cannot hide reliably. Or you want to get close and personal, so that you can either inflict sneak attack damage with your reaction or so that you can keep the enemy unable or unwilling to get out of an uncomfortable position that you put them into (eg inside the radius of a darkness spell). Not much to say abut the first scenario, quite a lot to say regarding the second. Let's say that you have a way to get (fast!) close to the enemy caster. Let's say that doing so carries an acceptable risk (eg the caster is not surrounded by their invincible guards of doom that can KO you with one hit). You have ways to counteract these (stealth and cunning action dash/disengage/hide being your greatest tools), but you wont always be able to, so these are downsides you need to have taken into consideration. But let's say you can deal with all that, and now you are adjacent to the enemy caster and you have cast a spell that will block his line of sight. Let's even say that the caster cannot pierce it, because it's a fog cloud or because they did not posess any sense enhancing abilities. What's to prevent the caster from just moving away? You can grapple of course (let's assume the spell was a pre casted darkness, so hopefully you can spare the action to grapple), but with only expertise and no extra attacks it is a bit dicey. You can threaten with an OA for big reaction damage (assuming you have a way to see through the obscurement, so rogue's blind sight or a feat/mc to get an ppropriate feature like devil's sight or blind fighting), but the enemy can still get out and cast (bonus points if you have sentinel though). This will only be good if you can repeat it a few times (so either move obscurement or have a way to draw the caster back in). Now let's say that all of the options above are extremelly bad for the caster on average. So what if they can teleport? Misty step wont work, cause they cannot see where they are tp'ing? But what if they have dimension door? And that's about how good rogues are as mage kilers. Not very. And it's not just dimension door. A caster can use other spells for escape or defense; dimension door is just obvious both because it's great but also because it is easily accessible as a 4th level spell. There you need counterspell and a way to see, though you need to know what the enemy is casting, and even if successful, this will allow the enemy to simply move out, so you are back to either moving obscurement (so darkness, which can be pierced easily) or to drawing the caster back in (which is a problem on its own). All while your far from foolproof plan being one dispel magic away from failing.



6) My conclusion
A) Rogues do get some stuff that can help them with mage hunting. They are not great at it, but with a bit of luck, and more importantly with the help of allies, anything is possible. As a solo carreer they would not be extremelly successful on the execution of the plan unless they stacked a lot of advantages through ingenius planning/trickery somehow.

B) To be a good mage slayer you dont need the feat.
b1) You need either a way to approach stealthily a mage and one shot them with high probability.
b2) Or, if you cannot do the first, you need a way to apporach stealthly a mage, jump into their face, take away their ability to cast spells (silence; secondarily by being an amazing counterspeller), and be able to lock them into position (sentinel or stunning strike) for a few rounds so you can take them down, hopefully before anything lurking around and is loyal to the mage kills you.

Your best bet for b1 are having stealthy allies, and you can use your stealth and then either your sneak attack damage of your spells&magical ambush to decent effect. Or find some way to add some nova that can amount more than just crit fishing sneak attacks).

Your best bet for b2 is to grab 5 levels of warlock (undying or fathomless) for silence and counterspell, or 6 levels of shadow monk (ideally with sentinel too) for shadow step, silence and stunning strike. The rest can go into rogue, but it's the non rogue levels that will do most of the work.

ps: For single class rogue mage slaying I would be tempted to go for either a yuan ti (poison immunity) or a warforged (dont need to breathe), and try out a stinking cloud hit&hide (backed up by blind fighting/sight, BB, stealth and athletics expertise, and maybe some mimicry) approach. Not the most effective, but it could be entertaining.

[solidork]

If you're not going the "be a caster to beat a caster" route, I've always liked Shadow Monks for this; you're a good infiltrator, mobile and can cast Silence without hindering yourself.