Creature — Thrull 1/1, B (1)
Common
Sacrifice Blood Pet: Add {B} to your mana pool.
"You are wrong," Volrath said. "I do not hate the living. They often prove quite useful to me." And then he laughed.
Illus. Brom

10/1/2009: Because combat damage resolves immediately after it is assigned, you cannot sacrifice Blood Pet in between assigning and dealing combat damage. The last chance you have to sacrifice it before combat damage is dealt is during the Declare Blockers step.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Classic (MTGO)
Legal in Commander