Quantum

Huge aberration, neutral

Armor Class 20 (natural armor)
Hit Points 448 (39d12 + 195)
Speed fly 40 ft.

STR	DEX	CON	INT	WIS	CHA
30 (+10)	18 (+4)	20 (+5)	11 (+0)	14 (+2)	17 (+3)

Saving Throws Wisdom +8, Charisma +9
Skills Acrobatics +16, Insight +14, Perception +14, Religion +12
Damage Immunities bludgeoning, piercing, and slashing from nonmagical weapons
Senses darkvision 60 ft., passive Perception 24
Languages Common, Quantum
Challenge 20 (25,000 XP)

Special Traits

• Displacement. The quantum projects a magical illusion that makes it appear to be standing near its actual location, causing attack rolls against it to have disadvantage. If it is hit by an attack, this trait is disrupted until the end of its next turn. This trait is also disrupted while the quantum is incapacitated or has a speed of 0.
• Innate Spellcasting. The quantum’s spellcasting ability is Charisma (spell save DC 17, +9 to hit with spell attacks). It can innately cast dimension door 1/day, requiring no material components.
• Quantum Form (3/day). A quantum can move in such a way as to appear in two places at once, at a distance no greater than 30 feet. This is a bonus action that provokes an attack of opportunity and lasts only one round. While occupying two spaces simultaneously, each representation of the quantum can perform one action normally. Using this ability, the same quantum could attack two different opponents, or attack one opponent while opening a door to escape, and so on. At the end of the round, both instances of the quantum return to the space it originally occupied before activating this ability.

Actions

• Multiattack. The quantum makes two attacks with its tentacles.
• Tentacles. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 31 (6d6 + 10) bludgeoning damage.
• Disintegration (3/day). Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: the target must make a DC 18 Constitution saving throw, taking 140 (40d6) force damage on a failed save, or 42 (12d6) force damage on a successful one. If the damage reduces the target to 0 hit points, it is disintegrated.

About

This creature seems to have no true shape as its outline flickers and changes seemingly at random. At first, it appears to have four tentacles, then in a flicker, eight more appear and waver menacingly before shimmering once more out of existence. Its general shape is serpentine, with an uncertain number of tentacles dangling beneath it. The only constants are its six glowing eyes, three on each side of what must be its head.

The quantums hail from beyond and between all planes. The first quantum is said to have followed a lost band of adventurers back after they became lost on a planar journey.

A quantum exists simultaneously in many dimensions at once, which gives it a flickering, seemingly insubstantial shape as if some mad god is continually creating and re-creating it on a whim. If its form could somehow be stabilized into only three dimensions, a quantum would resemble a flattened jellyfish with a knob at the top containing six unblinking eyes. It has an oblong body with many tentacles radiating out from beneath its body. The exact number of tentacles cannot be known, however, since stabilizing a quantum’s shape is a task yet to be undertaken and may not even be possible.

Quantums move by avoiding space entirely. A quantum hovers like some eerie jellyfish but doesn’t fly by conventional means. Instead, a quantum actually teleports short distances faster than the eye can detect, and in this manner, it appears to be hovering. A quantum can also teleport across greater distances. At one moment a quantum can be in one space and then in an instant it is somewhere else, having never been at any point between. The flickering form of a quantum allows it to attack with one tentacle, two, six, or as many as it needs. Attack-capable limbs seem to manifest themselves as they are needed, then vanish again as if they had never existed.

A quantum lashes out at its foes with its tentacles. Against a particularly powerful opponent, it uses its disintegration attack. When facing multiple foes, a quantum uses its quantum form to better its odds or make its escape.