Okay, so if I have 4 Bridge From Below, a Flame-Kin Zealot, and a Dread Return in my graveyard and 2 Narcomoebas on the battlefield, can I sacrifice the two Narcomoebas and one of the Bridge From Below zombies to pay the cost for Dread Return's flashback? Or do I need to have a third creature when I start to pay the cost?

Edited Benjemin Harris (Dec. 18, 2012 10:31:02 AM)

No you may not. Paying costs happens during casting a spell before the
bridge from below trigger from saccing the narcomoebas will even go on the
stack, so the zombies wont be on the battlefield until after the trigger
has resolved, long after the costs of playing the Dread Return are paid.

Okay. That's what I thought. I need to learn to use Cabal Theraby more efficiently, then. :D