Obelisk, the Tormentor

As an additional cost to cast this spell, sacrifice three non-token creatures. This spell can't be countered.

Shroud.

{t}, sacrifice two non-token creatures: destroy all creatures your opponents control. This ability can only be activated as a sorcery.

If Obelisk the Tormentor is cast or put onto the battlefield without paying it's mana cost, sacrifice it during the end phase.