Readied attacks vs. Casters mid-cast; concentration check?

[TheUser]

A Rogue in my group has been reading attacks against casters in hopes of interrupting them mid-cast.
"I wait for an enemy to start casting a spell before I attack"
The logic being that a caster taking a sneak attack as they begin casting will have to concentrate on the spell being cast or have it fail. I have allowed it for now but for some good reasons.

1) it's not 100% reliable: the attack has to hit along with a failure of the concentration check.

2) it's costly to the rogue's action economy: the rogue has to use their action and reaction which robs the rogue of uncanny dodge (and his arcane trickster reaction spells).

3) it reveals the rogue from hiding and makes them vulnerable mid-round: normally rogues can attack and re-attempt hiding on the same turn making them very risk-averse normally.

4) it lets me as a DM use the exact same tactic to counteract overpowered caster players in the group without using counterspell (which seems to just break their morale).

What do you guys think? Fair and balanced or absolutely brutal for casters? I happen to like the idea that a caster who gets smashed with a crossbow bolt in the hand/neck/chest mid-cast will have a difficult time completing the spell; it feels immersive and forces spell casters to take cover or play more intelligently in heated battles (like taking cover).

[Jerrykhor]

Just allow it, but use Shield spell when the rogue attacks and give a middle finger to the rogue:smallbiggrin:

[mephnick]

Oh god, queue 15 pages of debate about when reactions actually trigger.

[ad_hoc]

The readied action occurs after the trigger.

It is useful if a concentration spell was cast.

[Aaedimus]

Counterspell is pretty demoralizing. I do like this option more

[LeonBH]

It kind of invalidates Mage Slayer, but if no one has that feat, then I don't see why not.

Technically though, it doesn't force a concentration save if it was an instantaneous spell. You don't need to concentrate to cast a 1-action spell, otherwise casting any spell will break concentration.

You could also make it a spellcasting ability check on the part of the caster instead.

[TheUser]

The readied action occurs after the trigger.

It is useful if a concentration spell was cast.

The trigger "starts casting a spell" so after they start doesnt mean they finish ;)

[Kane0]

By RAW the attack happens after the spell is completed.
That said, I don't see anything wrong with doing it the way you do. Just be mindful of the Mage Slayer feat and other tricks like Action Surge to Ready and Readied Monk Stuns.

[Doug Lampert]

The trigger "starts casting a spell" so after they start doesnt mean they finish ;)

The target is a mage in combat, he's ALWAYS casting a spell. Turns and atomic actions are an abstraction.

You can work as if the abstraction were real and the action atomic, and there is no "start" or "finish" casting a spell, it's one action, it happens when it happens. It is not divisible because it is a single thing.

You can work as if the world were real, and the target is always casting so your "readied action" goes off instantly during your own turn as a normal attack but costing your reaction.

Either of the above is fine and consistent.

What the original poster is allowing is that his group's rogue will PRETEND that the abstraction is real and the spell casting is a singular event that happens during the caster's own turn during which everyone else is standing around frozen in time unless they have a readied action. And then having pretended that, he will ALSO claim that the spell cast takes some real time during which the rogue can react as if we were in the game world where things take time.

This is the commoner railgun again, we turn off the game abstraction and turn back on physics halfway through the thought process rather than picking one or the other and using it.

Reactions are pure meta-game, they only EXIST in the game abstraction where you are treating actions as atomic so that's where you should determine how they work. Ready and reactions are a game-mechanic to make up for the fact that actions aren't really atomic and you aren't really standing frozen in time while others act.

In world, if a spell takes a substantial fraction of 6 seconds to cast (and it does, an action represents most of what you do in 6 seconds) then MOST or ALL of the hits a mage takes in combat are "while he is casting", there's no reason to let some force concentration checks but not others.

[Elbeyon]

As long as you let readied attacks interrupt all actions, including other attacks, it should be fine.

[Arkhios]

Ruleswise you haven't done anything wrong if the spell being cast requires concentration. In fact, if a player decides to do this, it's their call.

However, if the spell being cast is an instantaneous spell, as mentioned, readied actions (reactions) happen after the trigger, so basically the spell should be allowed to be finished regardless of the hit from Readied attack. But, you're the DM, so you can impose additional penalties to the caster if you want to, and your reasoning isn't too bad, to be honest. It's just me, but in the case of instantaneous spells I think there are two (or three, actually) ways to have alternative results for the attack that hits.

If the spell has an attack roll, it's now made at disadvantage.

If the spell requires a saving throw, a) and it doesn't deal damage, the save is made with advantage, or b) the spell's damage is halved.

[the secret fire]

In world, if a spell takes a substantial fraction of 6 seconds to cast (and it does, an action represents most of what you do in 6 seconds) then MOST or ALL of the hits a mage takes in combat are "while he is casting", there's no reason to let some force concentration checks but not others.

Yup...which is why I prefer old-school magic rules. I run it like so at my table:

- magic users must make concentration checks based on the cumulative damage they've taken in a round before their turn comes up (no check if they don't get hit).

(...now giving something back...)

- follow up saves on save-or-suck spells are made a number of rounds later equaling how much the first save was failed by (e.g. you fail the save by 5, you make your next save check 5 rounds later).

[bid]

The trigger "starts casting a spell" so after they start doesnt mean they finish ;)
Using the same logic, sentinel might kill or push the attacker away, negating its triggering attack roll.

That's why I consider actions to be atomic unless the counter explicitely interrupts.

[Tanarii]

If it's not a concentration spell, it really doesn't matter if the attack happens after or during the casting of the spell, unless you kill the caster. Only concentration spells get interrupted by damage.

Edit: Point being, if you're already house ruling that, it doesn't really matter if you're also allowing a Ready attack to occur during casting. It's already house rule territory either way, so there's no point in worrying about if the timing of the attack is RAW or RAI or not.

[LeonBH]

The target is a mage in combat, he's ALWAYS casting a spell. Turns and atomic actions are an abstraction.

You are arguing that the RAW trigger for Counterspell is invalid. That makes you wrong from a rules standpoint.

[Jerrykhor]

The target is a mage in combat, he's ALWAYS casting a spell. Turns and atomic actions are an abstraction.

You can work as if the abstraction were real and the action atomic, and there is no "start" or "finish" casting a spell, it's one action, it happens when it happens. It is not divisible because it is a single thing.

You can work as if the world were real, and the target is always casting so your "readied action" goes off instantly during your own turn as a normal attack but costing your reaction.

Either of the above is fine and consistent.

What the original poster is allowing is that his group's rogue will PRETEND that the abstraction is real and the spell casting is a singular event that happens during the caster's own turn during which everyone else is standing around frozen in time unless they have a readied action. And then having pretended that, he will ALSO claim that the spell cast takes some real time during which the rogue can react as if we were in the game world where things take time.

This is the commoner railgun again, we turn off the game abstraction and turn back on physics halfway through the thought process rather than picking one or the other and using it.

Reactions are pure meta-game, they only EXIST in the game abstraction where you are treating actions as atomic so that's where you should determine how they work. Ready and reactions are a game-mechanic to make up for the fact that actions aren't really atomic and you aren't really standing frozen in time while others act.

In world, if a spell takes a substantial fraction of 6 seconds to cast (and it does, an action represents most of what you do in 6 seconds) then MOST or ALL of the hits a mage takes in combat are "while he is casting", there's no reason to let some force concentration checks but not others.
Too many assumptions here, you can't make stupid statements such as 'The target is a mage in combat, he's ALWAYS casting a spell.' What about clerics, pallys and other gish characters? You can't assume a wizard to always be casting too, he might be a Bladesinger.

I don't see much wrong with this part of the combat rules here. Its not hard to imagine a person being able to hold off his action until a trigger point happens, or react to something. What is so gamey about that? They certainly don't take a full 6 seconds to cast a spell, so why would you assume all the hits they take are in the middle of casting?

[opaopajr]

It's a Reaction not an Interrupt, so it doesn't matter how it goes onto the Stack, and thus there will not be any Mana Burn afterwards... :smallsigh: Oh crap, wrong game! :smalleek:

[Kane0]

It's a Reaction not an Interrupt, so it doesn't matter how it goes onto the Stack, and thus there will not be any Mana Burn afterwards... :smallsigh: Oh crap, wrong game! :smalleek:

To be fair the reaction vs interrupt part was also in 4e. Not sure why it was scrapped, the distinction is handy.

[Specter]

Here are the things that can happen:

- Readying the attack for when you see a spell component, or when the enemy starts casting a spell
This way you can attack before they cast a spell. But since the spell isn't cast yet, no concentration check will be needed.

- Readying the attack for when the enemy casts a spell
Here, you only attack after the spell is cast, but now the enemy has to make a concentration check.

Choose each wisely.

[Boci]

Depending on the exact set up of the combat, won't a clever spell caster counter this by moving away from you and then casting their spell? Sure the rogue will get an oportunity attack against, but then there is no way they will interrupt the spell.

[GorogIrongut]

I would have no problem letting the player do this because, they give up SO much to do it. And it's so easily countered by the mage. It'll work every so often, but has little chance to break the game. Plus... magic users are stronger than martial characters, so I don't mind giving them this mild debuff. Lastly, if the party gets to use it, then I get to use it against them, which for me = more shenanigans.

[Oerlaf]

You are arguing that the RAW trigger for Counterspell is invalid. That makes you wrong from a rules standpoint.

Shield, Absorb Elements, Counterspell.


These are the exceptions to RAW: specific beats general.

[LeonBH]

Shield, Absorb Elements, Counterspell.


These are the exceptions to RAW: specific beats general.

If you are saying Counterspell's trigger is valid, there is no reason to prevent someone else from mimicking that trigger.

[Provo]

TheUser, it seems like a good ruleing, and it's satisfying to your players.

Despite the drawbacks to the rogue, it could certainly be abused. Here are a few modifications you could make.

-The caster doesn't lose the spell slot if he is interrupted (unlike with counterspell).

-The caster has advantage if it is a non-concentration spell. This is because the spell is easier and wouldn't normally require a check anyway.

[Tanarii]

To be fair the reaction vs interrupt part was also in 4e. Not sure why it was scrapped, the distinction is handy.
It still exists. It just doesn't have a 'game mechanic' name. It's a Reaction that specifies timing that interrupts.

Like Counterspell. It specifically says you attempt to interrupt a spell in progress. That one literally uses the word interrupt, which was probably wise of them to make it completely clear on its 'timing'.

Or Shield, which says it goes off on a hit (ie after attack roll has been compared to AC), but also says the AC bonus applies to the attack that hit. That's effectively an interrupt, rules-wise.

[TheUser]

TheUser, it seems like a good ruleing, and it's satisfying to your players.

Despite the drawbacks to the rogue, it could certainly be abused. Here are a few modifications you could make.

-The caster doesn't lose the spell slot if he is interrupted (unlike with counterspell).

-The caster has advantage if it is a non-concentration spell. This is because the spell is easier and wouldn't normally require a check anyway.

I like the first one as an idea.
When I compare it to counterspell it's far less brutal as is but this seems like a good way to balance it especially if I use it against my players (and you can bet I will).