Undug Destroyer

{c}{r}, Discard this card: Deal 1 damage to target creature or player.
Whenever Undug Horror is put into a graveyard from anywhere other than the battlefield, exile it instead. If Undug Horror is in exile, whenever you excavate put an undug counter on it. Undug Horror costs {1} less for each undug counter on it. Whenever Undug Horror enters the battlefield or attacks, excavate 4 from any players' library, then shuffle any number of cards from your graveyard into your library.