Concentration Checks

[Username22221]

My group ran into a situation when grappling a spellcaster and couldn't find an answer. The creature was grappled and tried to cast a spell, but didn't want to provoke an AOO from everyone surrounding it (excluding the grappler who doesn't get an AOO). Does it make 2 concentration checks, 1 for being grappled, and 1 for casting defensively, if yes does it have to be in an order or how would that work?

[Jhaeman]

Yep, I'd say have multiple rolls because there may be different modifiers at play (such as the Combat Casting feat) and different results. The order doesn't really matter since they all have to be pass in order for the spell to succeed.

[Mysterious Stranger]

I agree with the multiple checks and depending on the circumstances he may need to make more than just 2. If while you are casting your character does anything else that requires a concentration roll you will need to make another check. For example, if you take damage while casting or are taking continues damage you need to make concentration checks for those as well.

[Azothath]

Username22221 wrote:

My group ran into a situation when grappling a spellcaster and couldn't find an answer. The creature was grappled and tried to cast a spell, but didn't want to provoke an AOO from everyone surrounding it (excluding the grappler who doesn't get an AOO). Does it make 2 concentration checks, 1 for being grappled, and 1 for casting defensively, if yes does it have to be in an order or how would that work?

depends on what it is doing and then what happens.

Casting defensively in a grapple, yes, RAW calls for two (Cast Defensively to avoid AoO then Grapple Casting check to cast spell).
Concentration Rules

Essentially Cstr's Conc +(CL +primary spell casting ability bonus + trait/feat/etc).
For Wiz 7 with Int 20(+5), Conc +12, then attempt 3rd level spell.
For Ftr 7 with Str 20(+5), CMB is usually +12.

Casting defensively(DEF) is DC 15 + 2*SplLvl. That DC is lower than the Grapple casting check.
In this example it is caster's 1d20+12 vs DC 21.

Casting in a grapple/pin for 3rd level spell DC = 10 +grappler's CMB +SplLvl. not their current grapple check!
Thus caster's 1d20+12 vs DC 25 (doesn't affect provoking AoO, best choice is to use a Wand as they do not provoke).

You should do the Casting Defensive roll first so you can ignore damage from provoking or take on a possible third check for damage.

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A wizard should never be in combat or grappled without protections(mage armor, shield, prot E/G, illusion of calm, blur, blink, mirror image, false life, ablative barrier, ...). A wand of vanish and obscuring mist should be kept in two spring-loaded wrist sheaths. See my Mage-killer build Flowing monk 2 Wizard 7