Obelisk the Tormentor

This spell can't be countered.
Indestructible, reach, shroud, trample

As an additional cost to cast this spell, sacrifice three nontoken creatures.
{1}{b},{t}: Sacrifice two nontoken creatures destroy
all creatures target opponent controls. Activate only
as a sorcery. Activate only once each turn.

If this spell wasn't cast sacrifice, it during the
beginning of the next end step.