Adamantine Encasing

You enhance your attack with the hardness of the mountain, causing your blade to be enveloped in a black adamantine layer. At impact with the target, it momentarily resembles a pickaxe for a moment.
You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. When the attack hits a living being, it suffers only 1d4 damage. When it hits a construct or object, the target suffers the weapon attack’s normal effects, and must make a Constitution saving throw. If it fails, it cannot regain hit points lost by the attack until it finished a shortrest or someone casts mending on it. The magically created Adamantine Encasing of the spell negates the normal effect of an Adamantine weapon, and a hit is not considered a critical hit.

This spell gains an additional damage bonus when you reach certain levels. At 5th level, the melee attack deals an extra 1d8 damage to objects and constructs. The damage roll increase by 1d8 at 11th level (2d8) and 17th level (3d8).