Maliran, Brutal Mind Mage

Player
Whenever a creature an opponent controls dies, target opponent puts the top 4 cards of his or her library into his or her graveyard.
Whenever a creature is put into an opponent's graveyard from his or her library, you may pay {1}{b}. If you do, you may destroy target creature with toughness 3 or less.
Mana Sorce - {u} or {b}