Elroth, Magistrate of Demise

When Elroth, Magistrate of Demise deals combat damage to an opponent, you may Haunt that opponent (Search that opponents library for a creature with converted mana cost equal to the number of creatures you control, and exile it, for as long as it is exiled, your opponent gets an emblem with "At the beginning of your upkeep, you lose 2 life")
When Elroth, Magistrate of Demise leaves the battlefield, shuffle all cards exiled with Elroth back into their owners library.