The Thénardiers

Whenever a creature enters the battlefield under
your opponent's control, you may pay {2}. If you
do, reveal cards from the top of that player's
library until you reveal an artifact card with
converted mana cost 2 or less. Put that card onto
the battlefield under your control. Shuffle the
rest in a random order back into that player's
library. If you didn't put a card onto the
battlefield this way, create a treasure.