Full round casting, reflex saves, area of effect spells

[KarinsDad]

Interestingly, there's rules support for the DC being 53, and the Resist Energy having no effect on the setting of that DC.

Not really.

If the spell affecting you deals damage, the DC is 10 + points of damage + the level of the spell you’re casting.

The implicit "damage" means "dealt damage" in the sentence above does not override the explicit "damage taken" means "damage taken" in the sentence below:

If while trying to cast a spell you take damage, you must make a Concentration check (DC 10 + points of damage taken + the level of the spell you’re casting).

 

[Hypersmurf]

The implicit "damage" means "dealt damage" in the sentence above...

I wasn't using anything implicit - I was looking at the table entry that says "Concentration DC: 10 + damage dealt" in the skill description.

The phrase 'damage taken' appears nowhere in the skill description, only 'damage dealt'; you're correct that p170 uses 'damage taken' instead.

However, both p70 and p170 refer to damage dealt when dealing with continuous damage, so Acid Resistance won't reduce the DC of the Concentration check imposed by, say, Melf's Acid Arrow, regardless of which is considered the primary source... (though if the damage is reduced to 0, you'd have a case for arguing that no Concentration check applies.)

-Hyp.