Lazav, Dimir Mastermind
{U}{U}{B}{B}Legendary Creature — Shapeshifter
Hexproof Whenever a creature card is put into an opponent's graveyard from anywhere, you may have Lazav become a copy of that card, except its name is Lazav, Dimir Mastermind, it's legendary in addition to its other types, and it has hexproof and this ability.