Ancient Cellarspawn 16 (Commander: Duskmourn: House of Horror)

Each spell you cast that's a Demon, Horror, or Nightmare costs {1} less to cast. Whenever you cast a spell, if the amount of mana spent to cast it was less than its mana value, target opponent loses life equal to the difference.

NM - $12.60
LP - $10.10
MP - $7.60
HP - $5.10
DMG - $2.60