Electro, Assaulting Battery (Marvel's Spider-Man)

Flying You don't lose unspent red mana as steps and phases end. Whenever you cast an instant or sorcery spell, add {R}. When Electro leaves the battlefield, you may pay {X}. When you do, he deals X damage to target player.

NM - $6.50
LP - $5.50
MP - $4.00
HP - $3.00
DMG - $1.50