Nagash, Lord of Undeath

Deathtouch, indestructible
When Nagash, Lord of Undeath enters the battlefield, return any number of creature cards
from graveyards with combined mana cost X or less
to the battlefield under your control. Each is a black Zombie in addition to its other types.

Nagash, Lord of Undeath's power and toughness
are each equal to the number of Undead you control.