Creature — Thrull 1/1, B (1)
Common
Sacrifice Blood Pet: Add {B} to your mana pool.
No thrull has ever been burdened with a long life.
Illus. Heather Hudson

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