A large and invasive species, the abyssal mimic loves dank, dark, deep places. Naturally, it is attracted to dungeons. It tunnels out a few chosen burrows along a dungeon's floor, preferring places with decent foot traffic. Once settled into place, it's lips become the cover of a floor trap, and its gullet turns inside out forming the spiked pit below. Considered a nuisance by most underground races, the monstrosity is pulled out wherever it is found. After all, wandering monsters digest just as well as adventurers. Nobody likes getting eaten.

Abyssal Mimic

Large monstrosity (shapechanger), neutral

Armor Class 11 (natural armor)

Hit Points 76 (9d10 + 27)

Speed 15 ft

Burrow 10 ft

Str 18 Dex 10 Con 17 Int 5 Wis 14 Cha 8

Skills Stealth +4

Damage Resistances necrotic

Damage Immunities acid

Condition Immunities prone

Sensesdarkvision 60 ft, tremorsense 10ft passive Perception 12

Languages -

Challenge 4 (1,100 XP)

Shapechanger.

The mimic can use its action to polymorph into a pit trap or back into its true, amorphous form. Its statistics 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 corpse cart adheres to anything that touches it. A Huge or smaller creature adhered to the corpse cart is also grappled by it (escape DC 14). Ability checks made to escape this grapple have disadvantage.

Dead Drop (Object Form Only).

While disguised as a pit trap, the mimic appears to be constructed from material identical to the floor around it. A successful DC 14 Wisdom (Perception) check discerns an absence of foot traffic over the section of floor that forms the mimics’s cover. A successful DC 14 Intelligence (Investigation) check is necessary to confirm that the trapped section of floor is actually the cover of a pit.

When a creature steps on the cover, it swings open like a trapdoor, causing the intruder to spill into the pit below. The pit is 10 feet deep, the bottom of which is lined with spikes (the mimic's teeth). Once the pit trap is detected, an iron spike or similar object can be wedged between the pit’s cover and the surrounding floor in such a way as to prevent the cover from opening, thereby making it 'safe' to cross. A creature that falls into the pit takes 3 (1d6) bludgeoning damage and 11 (2d10) piercing damage.

False Appearance (Object Form Only).

While the corpse cart remains motionless in its cart state, it is indistinguishable from a pit trap.

Grappler.

The mimic has advantage on attack rolls against any creature grappled by it.

Actions

Pseudopod.

Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 9 (1d10 + 4) 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: 9 (1d10 + 4) piercing damage plus 4 (1d8) acid damage.

Bonus Actions

Flood (Object Form Only).

If there is a creature within the mimic while its cover is closed, it floods the chamber with gullet acid inflicting 7 (2d6) acid damage to the creature.

Reactions

Snap (Object Form Only).

The mimic resets its floor 'cover', trapping a Large or Smaller creature inside. The cover can be opened with a successful contested Strength roll against the mimic from either the creature within or another creature within 5ft. However, these creatures are subject to the mimic's Adhesive trait.