To put it simply, this mimic likes pain. It started out in a dungeon as a scourge but it didn't produce enough. The sadistic creature changed into a rack but after a while left unsatisfied. When it took the shape of an iron maiden, oh, its dreams came true. The way its victims writhed as it ate it, the screams they made it could soon imitate! It was the perfect meal. Of course, the torturers loved having this terrible monster about both as a trusted guard dog and device. It also made disposing of bodies all the easier.

Maiden Mimic

Medium monstrosity (shapechanger), neutral

Armor Class 16 (natural armor)

Hit Points 112 (15d8 + 45)

Speed 15 ft

Str 18 Dex 12 Con 16 Int 7 Wis 14 Cha 11

Skills Stealth +7

Damage Immunities acid

Condition Immunities prone

Sensesdarkvision 60 ft, passive Perception 12

Languages -

Challenge 5 (1,800 XP)

Shapechanger.

The mimic can use its action to polymorph into an iron maiden 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 mimic adheres to anything that touches it. A Huge or smaller creature adhered to the mimic is also grappled by it (escape DC 15). Ability checks made to escape this grapple have disadvantage.

False Appearance (Object Form Only).

While the mimic remains motionless, it is indistinguishable from an ordinary an iron maiden.

Grappler.

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

Actions

Multiattack.

The mimic makes two pseudopod attacks.

Pseudopod.

Melee Weapon Attack: +7 to hit, reach 15 ft., one target. Hit: 7 (1d8 + 4) bludgeoning damage. If the mimic is in object form, the target is subjected to its Adhesive trait.

Bite.

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 15 (2d10 + 4) piercing damage plus 9 (2d8) acid damage.

Reel.

The mimic pulls each creature grappled by a pseudopod 10ft closer to it.

Shriek of Anguish (Object Form Only).

The mimic shrieks as if it has a trapped victim within it affecting all creatures that can hear it within 30ft. These creatures must succeed on a DC 13 Wisdom save or be Frightened and Restrained for the next minute. At the end of its of turns, an affected creature may repeat this save with the effect ending on success.

Reactions

Gulp.

After hitting a creature with its Bite attack, the mimic may attempt to grapple the target with a normal grapple check (the mimic has advantage). If the target fails, the mimic gulps it within itself and closes, The creature now has complete cover from all attacks. While gulped, the mimic may use a Bonus Action to make a Bite attack against the target with advantage. The mimic can only Gulp one target at a time. If the mimic dies or releases a target it ends up in a square within 5ft of the mimic.