Shapechanger. The mimic can use its action to polymorph into a finger or back into its true, amorphous form. When it attaches to a creature, it changes size, shape and color to match the target, no action required. It can also mimic cloth, metal, and other materials to blend in with any clothing on the hand. 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.

False Appearance. While the creature remains motionless or moves as a normal finger would while attached to a hand, .it is indistinguishable from a normal finger.

Digit Mimicry. While the mimic is attached to someone's hand, it can detect what the target intends to do with its hand and will move itself accordingly. Fr example, if the target uses its hand to grasp an object, the finger mimic will bend to help grasp it.

Parasite. The mimic has advantage on attack rolls against any creature it is attached to.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 6 (1d4 + 4) piercing damage, and it attaches to the target creature.

      A humanoid target must make a DC 12 WIS saving throw. On a failed save, it is charmed by the mimic for 24 hours or until it is removed, forgetting that it is a mimic and believing it to be one of its own fingers. This conviction is magical in nature and can't be broken with reason or persuasion. It will be unwilling to remove the mimic or let anyone else remove it. It can remake its saving throw every time the mimic takes an action that reveals its true nature. Once it succeeds its saving throw, its immune to this effect for 24 hours. While the target is charmed, the finger can use the target's Ac in place of its own, as is immune to damage from areas of effect. The mimic can be removed with a DC 12 STR check. If the creature is unwilling to let it be removed, ability checks made to remove the mimic have disadvantage.