Final Fusion

Normal Trap

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.

Rulings – Yugipedia

Printings:

Dragons of Legend: DRLG-EN018 (Super Rare) - 2014-04-25
Dragons of Legend: The Complete Series: DLCS-EN020 (Common) - 2020-09-10

Prices:

Cardmarket: 0.14 €
TCGplayer: $ 0.17