Concentration Checks vs. Multiple Distractions

[The Crusader]

I find this odd that this has never come up for our group before, but...

A spellcaster NPC (either a Cleric or an Oracle, I never saw her stats) was entangled and casting defensively. Under RAW that requires a (15 + spell level) and a (15 + double spell level) Concentration Check. I am of the opinion, however, that making two checks at the levels appropriate to each individual situation doesn't do justice to the RAI.

Parsing out the numbers:
Casting a 4th Level Spell while entangled = DC 19
Casting a 4th Level Spell defensively = DC 23

Concentration bonus for a Level 8 Spellcaster with 18 in the relevant stat = +12
Odds of Success = 35%

Concentration bonus for a Level 8 Spellcaster with 18 in the relevant stat and Combat Casting feat = +16
Odds of Success = 63%

So, my question is: Should a spellcaster facing two different distractions make two different checks, or one modified check?

If, for example, you decide that (15 + spell level) + (15 + double spell level) = (15 + triple spell level), then you get a modified DC 27. The odds of success change to 25% without Combat Casting and 55% with Combat Casting. Does this seem more appropriate? Or does it seem like a lot more math, where none is needed or desired?

[Noir le Lotus]

In my opinion, too much rolls end up slowing the game.

So go for the easiest solution : make only one check against the highest DC.

For situations like tumbling between multiple opponents, make one roll and compare to the differents DCs. The DCs beaten are considered successful, the others are fails and you apply the adequate consequences.

[Ashiel]

I'd make a check versus each effect. It's not like it really takes up all that much time. Even if you were sustaining continuous damage, got shot while casting, in a storm, while entangled, that's only 5 d20 rolls in rapid succession, and all with the same modifier, so it's even easier than counting out a Fighter's attacks.

Likewise, by my reading of the rules, if you get shot multiple times while casting the spell, the save DC rises each time (since each time you take damage you make a check with a DC 10 + damage taken while casting, which taken literally would be all the damage you've taken while casting).

I love playing casters, and even I think rolling multiple times is quite fair.

[Kthulhu]

The Crusader wrote:

If, for example, you decide that (15 + spell level) + (15 + double spell level) = (15 + triple spell level), then you get a modified DC 27. The odds of success change to 25% without Combat Casting and 55% with Combat Casting. Does this seem more appropriate? Or does it seem like a lot more math, where none is needed or desired?

I'd use this, because they're casting the spell one time with multiple distractions, not casting the spell twice.

[Noir le Lotus]

3 players with 3 different answers, I don't think we really help the OP :-p

[Kthulhu]

Noir le Lotus wrote:

3 players with 3 different answers, I don't think we really help the OP :-p

Sometimes that's how the cookie crumbles. I personally think the fact that different groups can interpret things different is a strength of the game, although I know there are those who disagree.

[Alex_00]

As far as I can tell RAW should be separate checks for each distraction. Though there is some debate as to whether combat casting should apply to more than just the roll to avoid an AOO.

In actuality I think you have a strong point that multiple distractions make it harder to concentrate that once, and it is silly to make multiple rolls as you couldn't actively concentrate multiple times in that time period and very few other instances involve multiple rolls of the same kind for a single action.

I think that would technically be a house rule. But two ways to do it for me would be to choose the maximum base (10 or 15) and the maximum variable modifier (for instance double spell level). Or choose the maximum base and add the two variable modifiers (so in your example 3x spell level). The latter is probably the way I would go.

It has profound effects though. For instance, if you rule that combat casting only ever effects the cast defensively roll then this would make the feat more useful. If you rule that combat casting affects multiple rolls then folding them all into one makes it much less effective.

[Claxon]

Make a check against each affect.

It actually gives a higher chance for failure because every d20 roll means a chance to roll low and miss the DC. It's a very effective strategy when dealing with a spell caster if you can ready actions to interrupt their spells with attacks.

Even though rolling more dice slows the game down, this is one case where you shouldn't skip.

Just like making attack rolls or saves.

Edit: Just realized this is a 5 year old thread. Answer probably doesn't matter to the OP.

But the correct answer is still roll for each.