Karthus, the Deathsinger

You may cast Karthus, the Deathsinger from
your graveyard or from exile.
Zombies you control have Persist. (When
this creature dies, if it had no -1/-1 counters on it,
return it to the battlefield under its owner's control with
a -1/-1 counter on it.)
{1}{u/b}{u/b}{t}: Surveil 2, then you may cast creatures
from you graveyard this turn.