Unspeakable Angel

Flying, deathtouch
Phase 4: Sacrifice a creature (When this creature
becomes target of a spell or an ability an opponent
controls or if you pay its phase costs, exile it with 4
phase counters on it. Remove a phase counter at the beginning of each turn. When there are no counters
left, put it back onto the battlefield.)

When Unspeakable Angel enters the battlefield,
destroy target creature with mana value 4 or less.