Whenever Rex, Cyber-Hound deals combat damage to a player, they mill (To mill a card, a player puts the top card of their library into their graveyard.) two cards and you get (two energy counters). Pay : Choose target creature card in a graveyard. Exile it with a brain counter on it. Activate only as a sorcery. Rex has all activated abilities of all cards in exile with brain counters on them.