Wendiigo

Trample
Changeling

When Wendiigo enters under your control, if no life was spent to cast it, sacrifice it.

Whenever Wendiigo dies, return it to the battlefield transformed as an Enchantment - Aura Curse attached to target opponent. Enchanted player creates a 1/1 black horror creature token with Indestructible and "Whenever a creature enters under your control you lose 4 life".