Every mimic takes perverse joy in deceiving others until it is time to strike. This miniature strain, being a mote smarter than the average mimic, finds sadistic pleasure in the act instead. As such, it has chosen to imitate navigator tools, most commonly a compass. More troublesome, the compass mimic has developed the ability to befuddle its prey in a myriad of ways. Its mere presence confuses a creature’s sense of direction, and once the monstrosity exerts its will it can even turn foes against one another. Once revealed, the compass mimic addles its meals, burrowing into its internal cavity before the poor creature can even react. Then it can feast at its leisure. 

Compass Mimic

Tiny monstrosity (shapechanger), neutral

Armor Class 15 (natural armor)

Hit Points 40 (9d4 + 18))

Speed 05ft

Str 5 Dex 18 Con 15 Int 6 Wis 17 Cha 18

Skills Stealth +8, Survival +7

Damage Immunities acid

Condition Immunities charmed, prone

Senses darkvision 60 ft., passive Perception 13

Languages -

Challenge 3 (700 XP)

Shapechanger.

The compass mimic can use its action to polymorph into a compass 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 14). Ability checks made to escape this grapple have disadvantage.

False Appearance.

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

Grappler.

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

Innate Spellcasting.

TThe compass mimics's innate spellcasting ability is Wisdom (spell save DC 14, +6 to hit with spell attacks). It can innately cast the following spells, requiring no material components:

3/day each: crown of madness

1/day each: confusion

Navigator's Bane (Object Form Only).

Whenever the compass mimic is part of a navigator's kit, a creature using the kit has Disadvantage when using that kit and on Wisdom (Survival) checks.

Actions

Pseudopod.

Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 1 (1d4 - 3) bludgeoning damage. If the mimic is in object form, the target is subjected to its Adhesive trait. If the target is a creature, it must succeed on a DC 13 Wisdom save or use its Stunned until the end of its next turn.

Bite.

Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 1 (1d6 -1) piercing damage plus 9 (2d8) acid damage.