Armor mimic

Multiattack

The mimic makes three attacks: two with its Mimic Hammer and one with its Shield Maw.

Mimic Hammer

Melee Weapon Attack: +11 to hit, reach 5 ft., one target.
Hit: 16 (2d10 + 6) bludgeoning damage plus 7 (2d6) acid damage.
If the target is grappled by the mimic, the attack deals an extra 10 (3d6) bludgeoning damage.

Shield Maw

Melee Weapon Attack: +11 to hit, reach 5 ft., one target.
Hit: 19 (2d12 + 6) piercing damage plus 7 (2d6) acid damage.
The target is grappled (escape DC 18). Until this grapple ends, the target is restrained.

Swallow Into the Chestplate (Recharge 5–6)

The mimic swallows one Medium or smaller creature it is restraining. The swallowed creature is blinded and restrained, has total cover against attacks and other effects outside the mimic, and takes 21 (6d6) acid damage at the start of each of the mimic’s turns.
If the mimic takes 30 damage or more on a single turn from a creature inside it, the mimic must succeed on a DC 18 Constitution saving throw at the end of that turn or regurgitate the creature, which falls prone in a space within 10 feet of the mimic.

Hungry Shift (Bonus Action)

The mimic armor shifts and snaps its body parts into place. The mimic chooses one creature it can see within 5 feet. That creature must succeed on a DC 18 Strength saving throw or be grappled (escape DC 18).
If the creature is already grappled by the mimic, it instead becomes restrained until the grapple ends.

Shield Snap

When a creature within 5 feet hits the mimic with an attack, the mimic snaps its shield-maw shut. The creature must make a DC 18 Dexterity saving throw or take  (4d6) piercing damage and become grappled (escape DC 18).

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.

Hammer Step

The mimic moves up to half its speed without provoking opportunity attacks.

Crushing Blow

The mimic makes one Mimic Hammer attack.

Living Clamp (Costs 2 Actions)

One creature grappled by the mimic takes 18 (4d6 + 4) bludgeoning damage and must succeed on a DC 18 Constitution saving throw or be stunned until the end of its next turn.

Acid Vent (Costs 3 Actions)

The mimic spews acid in a 20-foot cone. Each creature in that area must make a DC 18 Dexterity saving throw, taking 28 (8d6) acid damage on a failed save, or half as much damage on a successful one.