Valkyrie Chariot (MP20-EN090) [2020 Tin of Lost Memories]

Once per turn, you can either: Target 1 Fairy monster you control; equip this card to that target, OR: Unequip this card and Special Summon it. If the equipped monster would be destroyed by battle or card effect, destroy this card instead. When the equipped monster declares an attack: You can have it gain 500 ATK. (This ATK gain remains even if this card leaves the field.)