PrC Question

[merfolkotpt]

There is a prestige class that my brother told me about but i cannot remember what it is, any help would be great.
Things I know:
~Melee/Caster Hybrid
~Can drop a spell on a successful attack that it is immune too, my brother said fireball but it might be anything. So wade in, attack middle guy, drop 6d6 of fire damage that doesn't hurt me.
~Not a bladesinger, duskblade, hexblade.

Thanks for help.

[Swooper]

Jade Phoenix Mage, from Tome of Battle.