Ulamog, Devourer of Worlds

Indestructible, Annihilator 4
When Ulamog, Devourer of Worlds enters the battlefield, if it wasn't cast from your command
zone, exile it.
Whenever a player sacrifices a permanent, you
may put it onto the battlefield under your
control.
All lands lose all colors and types and are
colorless wastes. (they have {t}: Add {c} to your
mana pool)