Tendrils of Despair | Magic: The Gathering
Formats Tendrils of Despair is Legal in
Official Oracle Text for Tendrils of Despair
Target opponent discards two cards.
—Karn, silver golem
Official Rulings for Tendrils of Despair
4/15/2013 : You must sacrifice exactly one creature to cast this spell; you cannot cast it without sacrificing a creature, and you cannot sacrifice additional creatures.
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.