Xathrid, lord of Darkness

When you cast Xathrid, lord of Darkness exile it. You may use his abilities while he is in exile.
Deathtouch, Lifelink, indestructible, trample
{b}{b} sacrifice a creature. if at your end step there is a total of 25 combine power among creatures in you graveyard, you may cast Xathrid, Lord of Darkness from exile this turn.
{b}{b}{x} put {x} 2/2 black zombie tokens onto the battlefield
{b}{p/b}{p/b} gain control of target permanent