Copper Monster

Degrade Silver. Any silver plating on a nonmagical, silvered weapon that hits the copper monster is transmuted into a patina of copper. After dealing damage, the weapon takes a permanent −1 penalty to damage rolls, and it is no longer silvered. Nonmagical silvered ammunition that hits the copper monster becomes unusable after dealing damage.

False Appearance. While the copper monster is in dim light or darkness, it is indistinguishable from a rust monster.

Noble Scent. The rust monster can pinpoint, by scent, the location of gold & silver within 30 feet of it.

Multiattack. The copper monster makes two pincer attacks, or one antennae attack and one pincer attack.

Pincer. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 2) piercing damage.

Antennae. The copper monster degrades nonmagical objects of gold or silver it can see within 5 feet of it. If the objects aren't being worn or carried, the touch degrades a 1-foot cube of it (or 100 coins worth). If the objects are being worn or carried by a creature, the creature can make a DC 11 Dexterity saving throw to avoid the copper monster's touch.

Degraded metals are magically transmuted into a metal of lower value. Gold is transmuted into silver, and silver is transmuted into copper.

If the object touched is a silvered weapon that is being held, it degrades as described in the Degrade Silver trait.