Whenever Lazav, Scheming Shadow deals combat damage to a player, surveil 2 and each opponent mills two cards. Then, you may have Lazav become a copy of target creature card in a graveyard, except it's name is Lazav, Scheming Shadow, it's legendary, and it has this ability.

Transmute {U}{B} ({U}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)