Unscythe, Eater of Souls

This card also counts as a card named Unscythe, Killer of Kings.
{t}: Exile target creature.
When Unscythe becomes attached to a nontoken creature, exile that creature. If you do, Unscythe becomes a 0/0 legendary Avatar artifact
creature and gains vigilance and "This creature gets +X/+X, where X is the total power of all creature cards exiled with cards named Unscythe, Killer of Kings."
Equip {u}{b}{b}{r}