I'm in a campaign that will likely see underwater combat soon. My fire spell is clearly out.
Per DM ruling, electric spells become AoE (as we found out when I shocking grasp'd a wet kraken that was grappling several party members). While RAW doesn't specificly support this I can see the logic behind it and DMs can modify spell function for aqueous terrain if they wish (as stated in aqueous terrain section).
So I'm curious if there is a precident for acid spells under water. More specifically, I have the elemental spell (acid) feat and can convert my shocking grasps and fireballs to acid. Is there any reason why these shouldn't function as 'normal' when cast underwater then? (assuming water breathing etc.)
Chemically, Acid should work. But then, Fire should still work too (boiling water/steam hurts).
fire spells work just fine underwater. Its a DC 20 + spell level spellcraft check to make it conjure bubbles of steam. See the aquatic terrain section.
Fire: Nonmagical fire (including alchemist's fire) does not burn underwater. Spells or spell-like effects with the fire descriptor are ineffective underwater unless the caster makes a caster level check (DC 20 + spell level). If the check succeeds, the spell creates a bubble of steam instead of its usual fiery effect, but otherwise the spell works as described. A supernatural fire effect is ineffective underwater unless its description states otherwise. The surface of a body of water blocks line of effect for any fire spell. If the caster has made the caster level check to make the fire spell usable underwater, the surface still blocks the spell's line of effect.
why risk a 65% of the spell failing due to a failed caster level check? a 2/3 failure rate is high enough that I don't consider fire spells working 'just fine'.
I can see flaming weapons working as you don't need a caster level check. I'm guessing the magus arcane pool ability would work fine, as it is supernatural, not spell-like.
Spells or spell-like effects with the fire descriptor are ineffective underwater unless the caster makes a caster level check (DC 20 + spell level)
Does this mean even as via Elemental spell a fireball retains its fire descriptor and requires a caster level check, or does the acid change the descriptor and allow fire(acid) ball to be cast without the caster level check?
A dip into elemental sorcerer would change both descriptor and type for sure.
Personally I'd let metamagic feats work. It's kind of what they are there for.
the concept that lightning damage spells turn into aoe when cast underwater is from previous editions of D&D.
Sonic effects are the way to go under water.