Ancient Cellarspawn (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 - $8.50
LP - $7.00
MP - $5.00
HP - $3.50
DMG - $2.00