Rulings powered by The Netrep API. 'Armor Breaker's' effect starts a Chain when the equipped monster inflicts battle damage to the opponent's Life Points. It targets the card selected to be destroyed.
Duelist Pack 6: Jaden Yuki 3
Once per turn, you can equip this card to a Warrior-Type monster you control, OR unequip it to Special Summon this card in face-up Attack Position. While equipped to a monster by this effect, when that monster inflicts Battle Damage to your opponent, destroy 1 card on the field. (A monster can only be equipped with 1 Union Monster at a time. If the equipped monster would be destroyed by battle, this card is destroyed instead.)