Korosu, Nightmare of Mysthaven

Sacrifice three Enthralled creatures to cast
Korosu, Nightmare of Mysthaven.
Menace
When Korosu, Nightmare of Mysthaven enters
the battlefield, target creature becomes a 1/1 colorless Enthralled creature.
You may cast Korosu, Nightmare of Mysthaven
from your graveyard.