Void Sentry

+2: Deal X damage to any target. X is the number of "Void Sentry"s you control. You may have any number of "Void Sentry" cards in your library.
-3: Add 1 "Void Sentry" card from your library to your hand, or place 1 "Void Sentry" from your hand onto the battlefield.
-X: X is the largest number of counters on a card you control. Each player sacrifices a permanent. Return a card from your graveyard to your hand.