D&D 5E Interrupting spellcasting

[Fleetwood C. DeVille]

Is there a mechanism in 5e (other than Counterspell) to keep a spellcaster from casting?
I am thinking of old editions where you ready an action to attack and force a concentration check.

Cheers.

 

[Ovinomancer]

Heh.

Um, maybe. Crawford has tweeted that, in his DM NOT dev role, he would allow someone to ready to cast a silence spell if the target began casting a spell. I'm not keen on that, as I tend to only allow discrete events to be triggers (not the start of a discreet event), but it's all in the purview of the DM as to what's an allowable trigger.

Other than that, no, there isn't. Mage Slayer lets you punish someone for casting, but doesn't prevent it.

 

[Tony Vargas]

No. It'd be easy enough to implement: rule that spellcasting provokes and that being hit by the OA forces a Concentration check or the spell doesn't go off (and you don't expend the slot). Easy, nearly exactly what it was in 3e. Skip the concentration check and have the spell ruined & the slot lost automatically, and you're closer to AD&D. If you want spells to be interrupted by Ranged attacks you could let the attacker Ready with spellcasting as the trigger, but rule that casting takes long enough that the attack hits before it's finished, and apply the same rule as you chose for AoOs.

You could also rule that taking continuing damage on your turn, or taking damage since the end of your last turn forces you to make a Concentration save to cast at all, on your turn.

 

[mellored]

Just note that spells arn't as powerful as they used to be.

So if you weaken spell casters, your might want to compensate them a bit.

 

[Tony Vargas]

Just note that spells arn't as powerful as they used to be.

's'all relative: blasty spells aren't as powerful as when they scaled with level and without limit back in the day, and specific spells aren't as broken as in 3e, while many spells are arguably more powerful than they were in 4e, as well as casters getting a lot more of them.

So if you weaken spell casters, your might want to compensate them a bit.

OTOH, caster versatility is greater than ever, and save DCs scale with character level, while save bonuses might not scale at all, and daily-resource-heavy casters are only even hypothetically, theoretically, designed to balance with everyone else at all under the semi-mythical 6-8 encounters/day guideline.

OTOOH, PCs can use the same rules vs NPC casters.

I really wouldn't worry about it. Give it a try: If a given PC seems consistently, significantly, under-powered, just toss him the right magic item, he'll be fine. On the outside chance you do find casters across the board demonstrably overly weakened by maybe losing a spell now and then because they cast in melee, you can re-consider the rule, maybe soften it to an AoO after the spell's completed, or think of some way to 'compensate' casters (and be sure to apply it to NPC casters, too).

 

[Ralif Redhammer]

I feel like the concentration check is easy enough to use in the case of an interruption. But that being said, it also feels like it’s double-jeopardy for spellcasters to have to worry about getting their spell off, and then worry about maintaining it.

Also, if you do go that route, why can’t someone then interrupt the fighter, trying to distract them from landing their hit? Or the rogue lining up that perfect shot with a crossbow? My concern is that the game could devolve into just a bunch of “Imma let you finish…” moments.

 

[Tony Vargas]

It's also worth nothing that casting in melee being a Really Bad Idea was very much a feature of the classic game. Interrupting spellcasting goes all the way back, and wasn't done away with entirely until 4e. Even in 4e, most spells (ie Range & Area spells) provoked AoOs, even though being hit didn't prevent the spell from going off unless the caster was dropped.

5e is unique in giving casters a free ride this way.

Also, if you do go that route, why can’t someone then interrupt the fighter, trying to distract them from landing their hit?

Someone fighting in melee is already protecting himself from attacks, as a matter of course, and resolving an attack on your turn already represents making every effort to hit the other guy. A melee 'attack' also represents a whole round's worth of blows, even if it's only 1 attack (or 4 or 8) resolved on your turn. Most of them are 'interrupted' in some sense, or they'd all hit.

Even so, protection style, the Help action, and Sentinel can all already be used to interfere.

In contrast, loosing an arrow is loosing one arrow, and you could Ready to react to it...

Or the rogue lining up that perfect shot with a crossbow?

Already has Disadvantage for trying to make a ranged weapon attack while in melee. You can ready to attack him when he does, but pulling a trigger on a crossbow is prettymuch instantaneous, 'interrupting' seems unlikely.

Still, it'd be cool to have a more granular rule for Ready in general, maybe contested DEX checks or something, to give the Readied character a chance to resolve his action first. (Note that, applied litterally to spells, that'd just mean the caster takes damage, then, if he lives, goes ahead and casts.)

 

[Noctem]

By the rules, no. The only spell in the game designed to stop spellcasting is Counterspell.

However, there could be a custom trap for example that the DM would use to trigger off a spell being cast within an area. Custom things like this are the DM's prerogative. The trap could lay down a silence area of effect, replicate counterspell or whatever else. If you're the DM you can simply houserule something in to make it work like you want.

 

[Ralif Redhammer]

Certainly, but my concern is that when combined with the concentration rule and "save ends," it creates a situation of double-jeopardy for spellcasters, with multiple opportunities to disrupt their actions and negate the spell. Interrupting a spell was a lot more important when you were stuck with it for a predetermined duration once it was cast.

Also, a round is currently six seconds. Trying to interrupt a spell that can be cast that quickly seems like it'd be just as difficult to interrupt as a regular melee attack.

It's also worth nothing that casting in melee being a Really Bad Idea was very much a feature of the classic game. Interrupting spellcasting goes all the way back, and wasn't done away with entirely until 4e. Even in 4e, most spells (ie Range & Area spells) provoked AoOs, even though being hit didn't prevent the spell from going off unless the caster was dropped.

 

[Gimul]

Certainly, but my concern is that when combined with the concentration rule and "save ends," it creates a situation of double-jeopardy for spellcasters, with multiple opportunities to disrupt their actions and negate the spell. Interrupting a spell was a lot more important when you were stuck with it for a predetermined duration once it was cast.

Also, a round is currently six seconds. Trying to interrupt a spell that can be cast that quickly seems like it'd be just as difficult to interrupt as a regular melee attack.

You could use a 2E style initiative, but it would require a speed factor table for weapons (fairly easy to steal) and Casting times for spells (a little more tedious; could base it of base spell level for a shortcut). I agree you would also want to forgo the additional saving throws at the end of each turn.