Spell concentration checks question

[Christopher Rowe]

Are the DCs listed in Table 9-1: Concentration Check DCs at p. 207 of the Core Rulebook additive or cumulative? Neither?

I'm running an encounter tonight that takes place on the deck of a ship during a storm at sea. I know the Concentration Check DC list for the "Violent motion while casting" is applicable, because under the description of "Violent Motion" on p. 206 the "deck of a storm-tossed ship" is given as an example.

But the characters will also be fighting under conditions of violent weather—I'd say specifically the 5 + spell level Concentration DC Check Situation of "Wind with rain or sleet while casting."

The Concentration Check DC for "Violent motion while casting" is 15 + spell level.

So, given that both of those two "Situations" are in play, violent motion and wind with rain, should the Concentration Check DC be the greater of the two (15 + spell level) or the two added together (20 + spell level)? Or something else altogether that I'm not seeing?

[Jiggy]

I *think* they have to make both checks separately, and failing either costs them the spell.

[Gwaihir Scout]

Circumstance penalties or bonuses generally stack. I would add the two together.

[Christopher Rowe]

Jiggy wrote:

I *think* they have to make both checks separately, and failing either costs them the spell.

That's something I hadn't even considered, and it certainly makes sense. Thanks, Jiggy.

Anybody else?

[Dominigo]

Generally, I believe you are supposed to do an individual concentration check against everything that could interrupt the concentration of the caster during the casting of his spell. This means that in your case he would do a concentration check at DC 5 + Spell Level and a second check at DC 15 + Spell Level. If he got attacked while doing this, it would be a third check at DC 10 + Damage Dealt + Spell Level. If he also was entangled, he would make a fourth check at DC 15 + Spell Level.

If you would prefer to add them together, that is up to you, though it will mean that any caster being forced to make concentration checks from multiple sources will quickly have the DC scale to very high levels. Not that it is really unreasonable, though. I think a wizard in a net on the deck of a ship in a hurricane who is being stabbed by a sword probably wouldn't be able to concentrate very well at all.

[BillyGoat]

RAW, they'd have to make both checks, since neither is a modifier to an existing check, but a reason for having to concentrate in the first place.

In the interest of speed-of-play, I'd just have them make the higher of the two checks. Not to mention how pissed I'd be as a player if I succeed at the DC 15+Spell only to fail at the DC 5+Spell.

[Gwaihir Scout]

The wind and motion are both ongoing and affecting the caster simultaneously, though. I don't see where the rules say that each circumstance requires a different check. I agree that receiving damage prompts a separate check without the environment penalties.

Side note: If you tend to be on storm-tossed ships frequently, check out the Uncanny Concentration feat.

[SlimGauge]

Some checks you have to make seperately, because you can have modifiers that affect one of the causes but not the other.

Example: I'm casting in a threatened area in a rainstorm. My Combat Casting feat affects the concentration check to cast defensively, but not the check due to the adverse weather. I have to make two checks, one at a DC of 15 + double spell level (that I get to add my +4 feat bonus to) and one at a DC of 5 + spell level (that Combat Casting does not apply to).

If I had the trait "Focused Mind", that +2 would apply to both checks. If I had the feat "Uncanny Concentration" (see Scout's post above), the +2 would apply to the first check, and I wouldn't have to make the second check at all.

[Stephen Dimitrovich]

This is sort of an older post but I just rolled across this today. I think that "deck of a storm-tossed ship" would imply that there is in fact a storm already in progress for the purpose of this roll and thus no extra roll for rain and wind would be needed.

[Finlanderboy]

What about in an aqueous orb? Extremely Violent motion, on going damage, and entangled?