Karthus, The Deathsinger

Black Mist (At the beginning of the end step, you
may put the top three cards from your library into your graveyard; if you don't control any creatures with the
same name as this creature, return this creature to the battlefield tapped.)
When Karthus, The Deathsinger dies, you may
pay {2}{b}{b}; this creature deals 2 damage to all creatures your opponent controls.