I am currently in a campaign as a wizard who specializes in lightning descriptor spells. I dipped into Stormcaster for flavor and its Storm Spell Power extraordinary ability. I stumbled across Born of the Three Thunders and may have found some cool (possibly broken) synergy.
Storm Spell Power reads: You are truly skilled in the use of spells that wield the power of the stormy seas. Any spell you cast that has the air, electricity, sonic, or water descriptor is cast at +2 caster level.
Born of the Three Thunders applies the sonic descriptor to any electricity descriptor spell among other things.
Would a Born of the Three Thunders spell be cast at +2 or +4 caster level?