Tezzeret, Cruel Captain

Whenever an artifact you control enters, put a loyalty counter on Tezzeret. 0: Untap target artifact or creature. If it's an artifact creature, put a +1/+1 counter on it. −3: Search your library for an artifact card with mana value 1 or less, reveal it, put it into your hand, then shuffle. −7: You get an emblem with "At the beginning of combat on your turn, put three +1/+1 counters on target artifact you control. If it's not a creature, it becomes a 0/0 Robot artifact creature."

Loyalty 4