During either player's Battle Step, when a Fusion Monster you control battles an opponent's Fusion Monster: Target both those Fusion Monsters; negate the attack, and if you do, each player takes damage equal to the combined ATK of both those Fusion Monsters.
![Final Fusion [DLCS-EN020] Common](http://www.cardmerchanttakapuna.co.nz/cdn/shop/products/d0b7956d-f458-5583-8885-a240c439df66.png?v=1698530536&width=1445)