Displacement. The Watcher 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 Watcher is incapacitated or has a speed of 0.

Eldritch Tendrils. The Watcher can have up to six tendrils at a time. Each tendril can be attacked (AC 20; 10 hit points; immunity to poison and psychic damage). Destroying a tendril deals no damage to the Watcher, which can extrude a replacement tendril on its next turn. A tendril can also be broken if a creature takes an action and succeeds on a DC 15 Strength check against it.

Limited Magic Immunity. The Watcher can't be affected or detected by spells of 6th level or lower unless it wishes to be. It has advantage on saving throws against all other spells and magical effects.

Rejuvenation. The Watcher's body is dispersed into the weave when it drops to 0 hit points. The Watcher's body reforms after 1d10 days, regaining all its hit points and becoming active again. Only a wish spell, or killing the Watcher in a permanent antimagic field can prevent this trait from functioning.

Innate Spellcasting. The Watcher's spellcasting ability is Intelligence (spell save DC 18, +10 to hit with spell attacks). The Watcher can innately cast the following spells, requiring no material components:

At will: darkness, evard’s black tentacles, misty step

3/day each: banishment, disintegrate, dispel magic, geas, resilient sphere

1/day each: feeblemind, maze, plane shift

Multiattack. The Watcher makes four attacks with its eldritch tendrils. The Watcher can direct the tendrils at the same target or at different ones.

Eldritch Tendrils. Melee Weapon Attack: +10 to hit, reach 50 ft., one target. Hit: 10 (1d10 + 5) piercing damage plus 5 (1d10) force damage, and the target is grappled (escape DC 16). Until this grapple ends, the creature is restrained, and the tendrils can't constrict another target.

Elemental Barrage. The Watcher creates five glowing orbs in the air around it. The Watcher choose acid, cold, fire, force, lightning, necrotic, poison, psychic, thunder or any combination thereof for the type of orbs it creates and sends them streaking toward a point or points it chooses within 120 feet of it. Once the orb reaches its destination or impacts against a solid surface, the orb explodes. Each creature within 5 feet of the point where the orb explodes must make a DC18 Dexterity saving throw. A creature takes 6 (1d6 + 3) damage of the orb type on a failed save, or half as much damage on a successful one. The orbs all strike simultaneously.

Mending the Weave. As a bonus action on its turn, the Watcher can exert its will on the weave, undoing any spell damage dealt to itself or another creature that it can see within 20 feet of it. The beneficiary of this ability instantly regains 20 hit points.

Parry. The Watcher adds 5 to its AC against one melee attack that would hit it. To do so, the Watcher must see the attacker and have a free tendril to parry with.

The Watcher 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 Watcher regains spent legendary actions at the start of its turn.

Attack. The Watcher makes one weapon attack or casts a spell.

Elemental Resistance. The Watcher gains resistance to one damage type of its choice — acid, cold, fire, force, lightning, necrotic, poison, psychic, thunder — until the start of its next turn.

Elemental Barrage (Costs 2 Actions). The Watcher uses its Elemental Barrage.