Legendary Resistance (3/Day).

If Malaxxix fails a saving throw, it can choose to succeed instead.

Magic Resistance.

Malaxxix has advantage on saving throws against spells and other magical effects.

Actions

Multiattack.

Malaxxix makes two Forge Hammer or Whip attacks in any combination.

Forge Hammer.

Melee or Ranged Weapon Attack: +12 to hit, reach 10 ft. or range 60/180 ft., one target. Hit: 28 (4d10 + 6) bludgeoning damage, and the target can't take reactions until the end of Malaxxix's next turn. Hit or Miss: The hammer then magically returns to Malaxxix's hand.

Whip.

Melee Weapon Attack: +12 to hit, reach 30 ft., one creature. Hit: 15 (2d8 + 6) slashing damage, and the target has the restrained condition for 1 minute. The restrained target can make a DC 20 Strength saving throw at the end of each of its turns, ending the effect on itself on a success. Only one creature can be restrained by the whip at a time.

Mezzoloth Vortex (Recharge 5–6).

Malaxxix summons a vortex of whirling mezzoloths at a point it can see within 90 feet of itself. The vortex is a 30-foot-radius, 100-foot-high cylinder centered on that point. Each creature other than Malaxxix in that area must make a DC 20 Dexterity saving throw. On a failed save, a creature takes 35 (10d6) force damage and has the restrained condition while within the cylinder. On a successful save, a creature takes half as much damage and is pushed to the nearest unoccupied space outside the cylinder. The vortex lasts until the start of Malaxxix's next turn.

Legendary Actions

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

Fiendish Stride. Malaxxix moves up to its speed. This movement doesn't provoke opportunity attacks. When Malaxxix moves within 5 feet of a creature during this movement, that creature takes 5 (1d10) lightning damage. A creature can take this damage only once per turn.
Attack (Costs 2 Actions). Malaxxix makes one Forge Hammer or Whip attack.

Lair Actions

In its lair on initiative count 20 (losing initiative ties), Malaxxix can take one of the following lair actions; Malaxxix can't take the same lair action two rounds in a row:

Reassemble. Malaxxix chooses either itself or the palanquin. The target gains 19 (3d12) temporary hit points.
Slam. Malaxxix commands the palanquin to slam the ground. Each creature within 15 feet of the palanquin must make a DC 20 Strength saving throw. On a failed save, a creature takes 11 (2d10) bludgeoning damage and has the prone condition. On a successful save, a creature takes half as much damage only.
Surge. Malaxxix commands the palanquin to move up to its speed.

Regional Effects

The region around the Unborn Palanquin is warped by its presence, creating the following effects:

Cranial Discomfort. Creatures that spend more than 24 hours within 1 mile of the palanquin hear an incessant scraping sound in their minds.
Grinding Gears. Constructs within 1 mile of the palanquin move sluggishly. Constructs' speeds are halved, and they have disadvantage on Dexterity saving throws.
Swarming Insects. Insects and insectile Beasts within 1 mile of the palanquin become disoriented and aggressive, coalescing into unnatural swarms and attacking any creatures in sight.

If Malaxxix dies or the Unborn Palanquin is destroyed, these effects end immediately.