Thieving Amalgam (21) [Commander 2019]

At the beginning of each opponent's upkeep, you manifest the top card of that player's library. (Put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.) Whenever a creature you control but don't own dies, its owner loses 2 life and you gain 2 life.