2-level Conjuration
You hurl a molten rock, inflicting damage and melting even the strongest of armour. Make a ranged spell attack against one target in range. On a hit, the target takes 1d8 fire damage. If a hit target is wearing nonmagical metal armor, it becomes damaged and the target suffers -1 AC. The target's armor is rendered useless after it reaches a -5 AC, and is destroyed beyond repair by normal means.
When you cast this spell using a spell slot of 3rd level or higher, it deals an additional 1d8 damage and causes affected armour to suffer an additional -1 penalty for each slot above 2nd.