Rust Ray

You unleash a russet ray at a metallic creature or object, causing the air to smell of hot metal. This ray corrodes metal that it touches. Make a ranged spell attack against the target. On a hit, the ray deals 3d6 Acid damage to the target or creature, ignoring Hardness as it causes it to rust and corrode immediately. Metal armor hit by this spell takes normal damage and loses 1d4 points of Armor Class. If this spell reduces an object's Hit Points to 0 or reduces a piece of armor to Armor Class 10, it rusts away completely.   A supernatural item resists the corrosion. Make an ability check using your spellcasting ability. The DC equals 10 + the item's rarity tier: 10 for common or uncommon, 15 for rare or very rare, and 25 for legendary.   At Higher Levels. When you cast this spell using a higher level spell slot, increase the damage by 1d6 for each slot level above its base level.
 

You unleash a russet ray at a metallic object. The air around you smells of hot metal.   This russet ray corrodes metal that it touches. You must succeed on a ranged touch attack with the ray to strike a target. It can effectively destroy any nonmagical iron or iron alloy object. Such objects struck by a rust ray take 2d6 points of damage +1 per two caster levels (maximum +10), ignoring hardness. You can also target a weapon being wielded or metal armor being worn. Metal armor affected by this ray takes normal damage from the spell and loses 1d4 points of Armor Class through corrosion. If an item is reduced to 0 hit points, it is destroyed. Ferrous creatures struck by the ray take the same damage as objects.   Magic items can negate the effect with a successful Fortitude saving throw.   Material Component: Rust particles or a piece of a rust monster.