Allabar, Opener of the Way

Allabar
Gargantuan aberration, chaotic evil
Armor Class 22 (natural armor)
Hit Points 370 (20d20 + 160)
Speed 30 ft., fly 30 ft. (hover)
Str 30 Dex 26 Con 27 Int 29 Wis 30 Cha 28
Senses darkvision 200 ft. passive Perception 20
Languages telepathy 250 ft.
Challenge 24 (62000 XP)
Psionic Boost (Recharge 5-6). When Allabar hits a creature with a tentacle attack, it can deal an extra 22 (4d10) psychic damage to the target.
Actions
Multiattack. Allabar makes three tentacle attacks, each against a different target.
Tentacle. Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 24 (4d6+10) bludgeoning damage.
Wrath Of The Forsaken World (Recharge 5-6). Allabar releases its fury with a mental blast that fills a 60 foot cone. Each creature in this area must make A DC 24 Wisdom saving throw, taking 88 (16d10) psychic damage on a failed save, or half as much damage on a successful one.
Reactions
Psychic Feedback. When a hostile creature damages Allabar, it can force the creature to make a DC 24 Intelligence saving throw. On a failed save, whenever the target makes an attack roll or saving throw before the end of its next turn, the target must roll a d6 and subtract the number rolled from the attack roll or saving throw.
Legendary Actions
Allabar 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. Allabar regains spent legendary actions at the start of its turn.
Tentacle. Allabar makes one tentacle attack.
Devour Body. Allabar pulls all creatures at 0 hit points within 5 feet of it into its space. Each creature that enter’s Allabar’s space dies, and Allabar recharges Psionic Boost as long as at least one creature died to this effect.
Unravel Essence (Costs 3 Actions). Allabar targets a creature it can see within 20 feet of it. The targeted creature must make a DC 23 Constitution saving throw or its body begins to be unmade. While being unmade, the target takes 22 (4d10) force damage at the start of each of its turns. The target must repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If the target fails three of these saving throws, it is reduced to 0 hit points. Allabar can only have one creature affected by this at a time. If it uses Unravel Essence on another, the effect on the previous target ends.

A massive orb just over twenty feet in diameter, covered in large, baleful eyes and writhing tentacles.

How to Fight a World. The Opener of the Way is a full planet that wanders through the sky, using its influence to create star spawn. The only way to stop its dire plans would be to confront it directly, but doing so is nearly impossible without incredibly powerful magic. Allabar sits far beyond where almost any mortal magic could reach it, requiring a Wish, Divine Intervention, or perhaps planar travel to actually reach it. Even after arriving however, adventurers may be stumped at how to destroy an entire planet. The surface of the world has strange, unnatural life brought back from the Far Realm, as well as many star spawn that resulted from Allabar’s many conjunctions with other stars. Allabar’s eyes look out from the surface of the world, each one thousands of miles across as it stares out into the cosmos, watching for worlds to influence and destroy. The only way to confront the planet itself may be to descend into the core of the world and find the avatar there that acts as the world’s heart and brain.

Created and Abandoned. Allabar was created long ago as an experimental attempt at a thinking, living world. The gods that participated in this test succeeded, but feared the power that their creation held and cast it away into the Far Realm in an attempt to hide and forget about it. In this place, Allabar was warped and changed in body and mind, and millennia later found its freedom back in the material plane where it belonged. The Opener of the Way is filled with malice and rage towards those who cast it out, but its vengeance has expanded to encompass all the gods and their creations. It fosters the stars’ hatred towards mortal worlds, using those most easy to manipulate to cause destruction wherever possible.

Allabar’s Lair
Allabar’s lair is a misnomer. The living world is its own lair, able to warp and control its surface to hinder foes and aid allies, or view upon creatures present there. All those who seek to challenge the Opener of the Way are as gnats crawling upon its body, helpless to actually harm the creature.

Lair Actions
On initiative count 20 (losing initiative ties), Allabar takes a lair action to cause one of the following effects:

– Allabar targets a volume of unoccupied space or solid stone no larger than a 50-foot cube anywhere it can see, turning the open space to solid stone or vice versa.
– Allabar causes up to four star wisps to manifest anywhere it can see. The star wisps obey its telepathic commands, which can reach anywhere on the planet. They last until the next initiative count of 20, when they disappear again.
– A grasping tentacle sprouts from the ground anywhere within Allabar’s line of sight. Each time a creature hostile to Allabar ends its turn within 10 feet of the tentacle, the creature takes 10 (1d10+5) magical bludgeoning damage. This tentacle is immune to damage and lasts until the next initiave count of 20, when it withers away.

Regional Effects
The following effects can occur anywhere on the planet so long as Allibar’s core lives:

– An eye opens on the wall, ground, ceiling, or any other solid surface. The eye is stationary. Allabar can see through the eye. The eye can be harmed (AC 1, 5 hp, immune to psychic damage, vulnerable to piercing and slashing). The eye remains until Allabar ends the effect (no action required).
– Open rifts to the Far Realm open up, releasing minor aberrations and reality warping energy before sealing up again.
– Star spawn manifest across the world as Allabar moves into conjunction with other stars.

If Allabar dies these effects fade immediately, though the aberrations and star spawn released by them remain.

This one was quite a lot of work, making lair actions and regional effects for it on top of the actual stat block. Allabar might not actually appear in the adventure I’m looking to convert, but its presence is so important that I thought it deserved conversion as well. Originally from the Monster Manual 3.  If there is a monster from 4th edition that you want to see converted to 5e, feel free to send me a message. If you like this post, consider following my Patreon to get access to content like this a week ahead of everybody else, plus updates on other projects I’m working on!