Worthy Cause | Magic: The Gathering
Formats Worthy Cause is Legal in
Official Oracle Text for Worthy Cause
As an additional cost to cast Worthy Cause, sacrifice a creature.
You gain life equal to the sacrificed creature's toughness.
Official Rulings for Worthy Cause
4/15/2013 : Players can only respond once this spell has been cast and all its costs have been paid. No one can try to destroy the creature you sacrificed to prevent you from casting this spell.