Soul Devourer

Curse X (The curse cost must be paid in life in addition to the spell's mana cost.)
Once Soul Devourer enters the battlefield, all human creatures take 2 damage.
When Soul Devourer enters the battlefield, out X Soul counters on it. When it is equipped, equipped creature gains as +Y/+0, where Y is the total number of Soul counters on Soul Devourer. Whenever an equipped creature dies, add 1 Soul counter on Soul Devourer. If equipped creature was a black creature, add an additional Soul counter on Soul Dev