Watcher

Light Sensitivity. While in bright light, the watcher has disadvantage on attack rolls and Wisdom (Perception) checks that rely on sight.

Damage Immunity. The watcher is immune to all damage types except for light, fire, lightning, and dimensional damage.

Charge. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 14 (2d8 + 5) bludgeoning damage.

Hooves. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 (2d4 + 2) slashing damage.

Phantasms (Recharges after a Short or Long Rest). The watcher magically creates three illusory duplicates of itself if it isn't in bright light. The duplicates move with it and mimic its actions, shifting position so as to make it impossible to track which watcher is the real one. If the watcher is ever in an area of bright light, the duplicates disappear.

Whenever any creature targets the watcher with an attack or a harmful spell while a duplicate remains, that creature rolls randomly to determine whether it targets the watcher or one of the duplicates. A creature is unaffected by this magical effect if it can't see or if it relies on senses other than sight.

A duplicate has the watcher's AC and uses its saving throws. If an attack hits a duplicate, or if a duplicate fails a saving throw against an effect that deals damage, the duplicate disappears.