Since the days of Advanced Dungeons and Dragons, the mimic has been one of the dirtiest tricks a dungeon master can pull on incautious players: a “door” or (usually) “treasure chest” that turns out to be a carnivorous monster. How on earth could such a thing evolve? At some point in prehistory, the mimic’s ancestors must have disguised themselves as natural objects, using octopus-like camouflage, only later adopting the forms of manmade objects after exposure to humanoid beings. This suggests a unique, specialized intelligence, akin to the ability of parrots and certain other birds to mimic speech . . . but one that’s used to lure and capture prey.
With strong physical ability scores across the board but especially high Strength and Constitution, the mimic is a “brute” creature adapted to close-range fighting. Yet it also has high proficiency in Stealth, along with darkvision: this is an ambush predator as much at home underground as aboveground. It has a sticky surface with which to ensnare its prey and advantage on attacks against any creature it’s caught this way.
The mimic’s particular combination of features is so calculated, there’s really only one way for it to behave:
- The mimic chooses a disguise (Shapechanger) and lies in wait for prey to approach (False Appearance).
- The mimic Attacks (action) with surprise, using its Pseudopod to grapple its target, which has disadvantage on its escape checks because of the mimic’s Adhesive surface.
- Against a grappled victim, the mimic switches to its Bite Attack (action), on which it has advantage (Grappler) and which does more damage than its Pseudopod attack.
- This is my own extrapolation: Once its victim is reduced to 0 hp, the mimic swallows it and proceeds to digest it, continuing to do 1d8 acid damage to the victim each turn until he or she is dead.
What if another party member attacks the mimic while it’s trying to consume its prey? My take is that it will simply avoid that attacker to the best of its ability, which is to say, it will move away at the greatest speed it can (half maximum movement, or 7 feet per turn, for Small or Medium-size victims), potentially subjecting itself to opportunity attacks, while continuing to Bite (action) its grappled prey. The mimic’s Intelligence is only 5; the “zone of control” concept is far beyond its comprehension.
Mimics are evolved creatures and do have a self-preservation instinct. However, they’re also slow, so outrunning an enemy isn’t a realistic proposition. A mimic that’s seriously injured (reduced to 23 hp or fewer) will let go of its prey, revert to its amorphous form and back away. Effectively, this is a Disengage action: although the mimic isn’t intelligent enough to know what disengaging is, the way it backs off is the same as a deliberate Disengage action for all intents and purposes. It no longer has the Adhesive property, and on its next turn, it will Attack (action) the next creature that comes within its reach with its Bite; if no creature pursues it, it will Dash (action) away in reverse, always keeping its mouth turned toward those who drove it off.
But let’s take a step back for a moment and read the description of the Adhesive feature carefully: “The mimic adheres to anything that touches it” (emphasis mine). Not “any creature”—anything. To me, that means that if you strike the mimic with a melee weapon, the weapon sticks to it! Now, the rest of the description is less helpful: “A Huge or smaller creature adhered to the mimic is also grappled by it (escape DC 13). Ability checks made to escape this grapple have disadvantage.” It doesn’t say anything about how to free an object stuck to the mimic.
It seems reasonable to me that a player character who wants to free his or her weapon from the mimic’s gluey surface should have to make the same “escape” check as a PC who’s grappled by it. Thus, you can hit the mimic with your sword on round 1, but you have to spend round 2 pulling it loose (DC 13 Strength check, disadvantage) before attacking again on round 3. That should add interest to a fight that otherwise has little to offer in the way of tactics or maneuvering. It will also give ranged fighters and spellcasters a leg up on the melee fighters (although ammunition fired into a mimic won’t be retrievable).
Next: Dodge, Dash or Disengage?