Wand of Wasting (5e Equipment)
From D&D Wiki
Wand, rare (requires attunement)
A hodgepodge of materials thrown into the shape of a wand and enchanted to waste away everything it touches.
Appearance. A thick wand exactly 11 inches in length. Blotches of stone, crystal, silver, and some black metallic material make up the item, as if scraps from a smithy had been bundled together and filed into an approximation of a wand. The suggestion of a three-armed spiral winds from the middle to the tip.
Attunement. A creature that holds the wand while not attuned to it takes 1 necrotic damage and 1 acid damage every round that it remains in physical contact. A creature attempting to attune to the wand can take reasonable precautions to minimize contact while doing so.
Wasting. When the wand comes into contact with a nonliving surface, object, structure, or construct, the material it touches begins to rapidly degrade. The material's maximum hit points and AC are reduced by 1 every round that the wand remains in contact with it, to a minimum of half of its original maximum hit points and AC, respectively. Magic items with a rarity greater than common are not affected.
Empowered Magic. While using the wand as an arcane focus, any spells cast by an attuned spellcaster that deal damage to a creature or object also reduce the target's maximum hit points by an amount equal to half the damage dealt. A target's maximum hit points cannot be reduced below 1 by this effect.