Shapechanger. The mimic can use a bonus action to polymorph into any weapon or back into its true, amorphous form. If the mimic polymorphs into a melee weapon, it ignores the heavy property. If the mimic polymorphs into a ranged weapon, it ignores the ammunition property. If the mimic polymorphs into a weapon with the thrown property, it is considered a melee weapon, even if used make a ranged weapon attack. Its statistics, other than the damage and range of its weapon attacks, 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.
Adhesive (Object Form Only). The mimic adheres to anything that touches it. A Large or smaller creature adhered to the mimic is also grappled by it (escape DC 12). Ability checks made to escape this grapple have disadvantage. The mimic can excrete, cease excreting, or dissolve its adhesive at-will.
Adhesive Shot (Object Form Only). The mimic's projectiles adhere to anything they hit. A Medium or smaller creature adhered to by one of the mimic's projectiles is also restrained by it (escape DC 12). Ability checks made to escape the restraint have disadvantage.
False Appearance (Object Form Only). While the mimic remains motionless, it is indistinguishable from an ordinary weapon.
Grappler. The mimic has advantage on attack rolls against any creature grappled by it.
Innate Spellcasting. The mimic's innate spellcasting ability is Strength (spell save DC 12). The mimic does not need to concentrate on concentration spells and can innately cast the following spells, requiring no material components:
At will: elemental weapon (self only, 5th-level spell, +2 to attack rolls, 2d4 acid damage), true strike
Weapon Attack. Melee or Ranged Weapon Attack: +4 to hit, reach or range of the weapon the mimic has polymorphed into, one target. Hit: The weapon damage die of the weapon the mimic has polymorphed into + 2. If the mimic is polymorphed into a melee weapon the target is subjected to its Adhesive trait. If the mimic is polymorphed into a ranged weapon the target is subjected to its Adhesive Shot trait.
Description
Weapon mimics pose as well made or even magical weapons to make themselves desirable to adventurers. They seek out caches of treasure or armories to hide among valuable objects or other weapons. Once picked up by an adventurer, a weapon mimic will travel with its new owner. By night, while the owner sleeps, the mimic will rummage through their belongings in search of food. If discovered (usually when a new owner attempts to identify it) a weapon mimic will often try to negotiate; offering to serve the adventurer as its weapon in exchange for regular payments of food.
As an amorphous living thing, a mimic is capable of adjusting its center of mass without impacting its performance, allowing its to be wielded effectively with ease by virtually anyone. They are even able to replicate ranged weaponry by forming and firing projectiles from their own flesh; each one a tiny simulacrum of the original which upon hitting a target, reverts to an amorphous form and grapples it.
Variant: Mimic Weapon
Some weapon mimics are willing to serve as weapons for other creatures. A mimic acting as a weapon gains the following trait:
Mimic Weapon. The mimic can be wielded as a weapon, and functions as whatever weapon it polymorphs into. While acting as a weapon for another creature the mimic takes no actions of its own. An attuned wielder can command the mimic to polymorph into a different weapon as a bonus action. The wielder can use an bonus action to command the mimic act as a dancing sword, regardless of what type of weapon the mimic is polymorphed into. The wielder can also command the mimic to cast a spell from the mimic's Innate Spellcasting trait, requiring the spell’s normal casting time and using the mimic's spellcasting DC.
When an attack using the mimic as a weapon hits, the target is subjected to the mimic's Adhesive trait if the mimic is polymorphed into a melee weapon, or its Adhesive Shot trait if it is polymorphed into a ranged weapon. Additionally, ability checks made to disarm the mimic's wielder by removing the mimic from their grasp have disadvantage. While being wielded as a weapon, the mimic shares its Grappler trait with its wielder against any creature subjected to its Adhesive trait.
The mimic is immune to game effects that would damage or destroy weapons with acid such as a black pudding's Corrosive Form trait. Non-acid game effects that would damage or destroy weapons deal 1d6 damage to the mimic instead of lower its damage rolls. If an attack or game effect would reduce the mimic to 0 hit points while it is being wielded and its wielder has at least 1 hit point, the mimic drops to 1 hit point instead. While the mimic has 5 hit points or less, it cannot be used to make weapon attacks, and the wielder loses all benefits provided by the mimic. The mimic is considered a destroyed weapon until its hit points rise above 5.
I had my adventurers explore an evil mage's ooze laboratory, and the barbarian picked up a neat sword. It's been with them for a while now. No ones the wiser yet. I've been trying to figure out what to do for the creature's monster stat block/magic item description for a while. I've just been making stuff up as I go, but then I found this. I'm glad this homebrew stat block is here. As a DM, I would be fine with using the creature as is. The bargaining nature of the mimic adds a layer of complication that would offset anything unbalanced about the players using it as a "magic item".
If I were to offer a suggestion for balancing the creature for lower level parties, I would perhaps limit elemental weapon to x/day uses, or bump up the creature''s CR when determining the parties level. It's basically a very rare magic item as it is now, which won't unbalance parties above level 10. But of course I gave it to a level 5 party, so that's on me.
Thanks for writing this stat block, Sam.
Glad you can get some use out of it! If your interested, I also wrote up the item version in case DMs wanted to keep the Mimic's identity a secret for a while. It can be found here. I've also been using this image to represent the monster/item.
The reason I gave it elemental weapon as an at-will spell, but restricted it to acid damage is to mechanically imitate the bite attack of a mimic. The piercing damage of a usual bite is substitute by the weapon damage of whatever weapon the mimic is polymorphed into while the elemental weapon spell adds the bite's additional acid damage (usually 1d8). The spell also turns it into a weapon with a +2 to attack rolls because from a lore perspective, the mimic is working with its wielder, lending them its strength in a very literal sense, because the mimic's Strength (for most melee weapons) and Dexterity (for finesse and ranged weapons) modifiers are both +2.
The elemental weapon makes more sense now. Question on the use of true strike. Is it a bonus action to command the mimic to use true strike (making it essentially a bonus Help action), or is the player using their action to cast true strike?
mechanically, it would work like a magic item that grants the player the use of a spell. It would have the same casting time as usual, using the player’s actions, but the mimic’s abilities. So in the case of true strike, 1 action.