Shapechanger. The mimic can use its action to polymorph into a Small or Medium humanoid it has seen, or back into its true, amorphous form. Its statistics, other than its size and speed, are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.
Grappler. The mimic has advantage on attack rolls against any creature that is grappling it or that is grappled by it.
Solvent (Humanoid Form Only). At the start of each of the mimic's turns, any creature adhering to it with adhesive takes 4 (1d8) poison damage, and must succeed on a DC 13 Constitution saving throw or be poisoned for 1 minute. The mimic can use its bonus action to instantly succeed on an ability check or saving throw to escape being grappled or restrained by adhesive or webs.
Pseudopod. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) bludgeoning damage. If the mimic is in object form, the target is subjected to its Adhesive trait.
Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) piercing damage plus 4 (1d8) poison damage.
Description
Amimics are a variety of amorphous shapechanging predators that have developed a series of unique adaptations to fill a unique niche in the ecology of the Underdark or in dungeons: they prey on mimics.
Amimics will polymorph themselves into a humanoid shape and wander through caverns and tunnels in search of crafted objects. When it finds one, it interacts with it; opening chests and doors to attempting to pick it up. If the object does not react, the amimic abandons it, seeking out another. If the amimic finds it cannot release its grasp on the object: it has found what it is looking for.
When a mimic reveals itself to the luckless humanoid that has touched it, it soon find that the meal to be had is not its own.
Like mimics, amimics secrete a substance from their skin. Unlike mimics, it is a toxic solvent that dissolves adhesives, rendering one of a mimic's biggest weapons and defense mechanisms useless and turning it against the monster.
My players fought one as a boss. the rolls: 20 17 18 20. Way more than the health.
Does the solvent work as Universal Solvent? (for Sovereign Glue)
Probably not, but it would be cool if it did.
Ultimately, that's a decision for the DM. If it were my table, I'd let a player harvest the solvent as an ingredient to craft universal solvent, but wouldn't have it function as the item as-is.