Arcane Mimic

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 18). Ability checks made to escape this grapple have disadvantage.

Disciplinary Evasion. The mimic adds it's charisma modifier to it's AC.

False Appearance (Object Form Only). While the mimic remains motionless, it is indistinguishable from an ordinary object.

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

Innate Spellcasting. The mimic's innate spellcasting ability is Charisma. It can innately cast the following spells, requiring no verbal or somatic components:

At will: distort value, identify, levitate, 

3/day each: dispel magic, greater invisibility, incite greed,

1/day each: animate objects,

Magic Resistance. The mimic has advantage on saving throws against spells and other magical effects.

Magical Sickness. A creature that fails a saving throw must make a DC 16 Intelligence saving throw. On a failure, the creature is diseased for 1d4 hours. The diseased creature can cast only cantrips if it knows any at all.

Shapechanger. The mimic can use its action to polymorph into an object 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.

Spellcasting. The mimic is an 13th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 16, +9 to hit with spell attacks). The mimic can cast the following spells:

Cantrips (at will): create bonfire, dancing lights, fire bolt, message, prestidigitation, shocking grasp,

1st level (4 slots): absorb elements, catapult, shield, chaos bolt,

2nd level (3 slots): blindness/deafness, enhance ability, warding wind,

3rd level (3 slots): melf's minute meteors, slow,

4th level (3 slots): confusion, stoneskin,

5th level (2 slots): creation, telekinesis,

6th level (1 slot): globe of invulnerability,

7th level (1 slot): symbol,

Pseudopod. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) bludgeoning damage plus an extra 10 (3d6) force damage. If the mimic is in object form, the target is subjected to its Adhesive trait.

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 8 (1d8 + 4) piercing damage plus 13 (3d8) acid damage.

The mimic can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The mimic regains spent legendary actions at the start of its turn.

Cantrip. The mimic casts a cantrip.

Font of Power (2 actions). The mimic rolls a d6 and regains a spell slot of that level or lower. If it has no spent spell slots of that level or lower, nothing happens.

Potent Spellcasting (2 actions). The mimic has advantage on spell attack rolls and creatures have disadvantage against spell saving throws until the end of the mimics next turn.