Obelisk the Tormentor

Summon (Your creatures can help cast this spell.
Each creature you sacrifice while casting this spell
pays for {1} or one mana of the creature's color.)
Split second, Shroud
When Obelisk the Tormentor enters the battlefield, if you didn't cast it from your hand, sacrifice it at the beginning of the next end step.
{t}, Sacrifice two creatures: Destroy all creatures
target player controls.