Ayara's Oathsworn (Showcase) (MAT-061) - March of the Machine: The Aftermath: (Showcase)

Menace
Whenever this creature deals combat damage to a player, if it has fewer than four +1/+1 counters on it, put a +1/+1 counter on it. Then if it has exactly four +1/+1 counters on it, search your library for a card, put it into your hand, then shuffle.