Seeing your avatar... a warlock's curse should totally be "I'm watching you, Focker!" like in "Meet the Parents"!Gwen, the party Feylock announces her curses with, "Prepare for Oblivion!". I always liked that one.
Back when I played an Infernalock (Wormwood v1.0), I hammed it up right out of Superman 2: "Son of an goblin! KNEEL before Wormwood!"