Arcane Plague

Destroy target creature.
A creature can only be targeted by one copy of this spell or the original simultaneously.
Until your next end step, you cannot lose the game.
When you cast this spell, create X copies of it, where X is the number of instant and sorcery cards in graveyards.
For each copy of this spell that isn't targeting a creature, each player takes three damage.
All that dead mana... They never stood a chance.
- Nicol Bolas