(While Jack is frozen, Prue pricks him with a knife. Jeff walks in, and Piper freezes him as well.)
Prue: Okay, there's two of them?
Piper: Twin warlocks?
Prue: Or maybe they're just twins. Okay, you unfreeze them. If that prick doesn't bleed... (she points to Jack, then Jeff) then that one's dead, too.