Astral searcher

Immateriality. Astral searcher is in a state between existence and non-existence. When moving, it does not provoke attacks.

The feeling of mind. Astral searcher does not have vision in the usual sense. Instead, the Astral searcher can sense all sentient beings within 120 feet of it while it is conscious. In addition, if a spell is used on the Astral searcher to find out its location, it will also find out the location of the caster at the time of casting the spell if the caster was on the same plane as the Astral searcher.

Tentacle. Melee Weapon Attack: +2 to hit, reach 5 ft., 1 target. Hit: 3 (1d8  - 1)  Force damage. 

Ailing light. Astral searcher releases a pale green beam of light emitting a feeling of weakness. RangedWeapon Attack: +8 to hit, range 60 ft., 1 target. Hit: 17 (3d8 + 5) Necrotic damage.

Search. Astral searcher focuses on a creature whose mind can sense. One creature within 120 feet must pass the Wisdom Saving Throw (difficulty: 13) otherwise it will become the target of the Astral searcher. The next time the Astral searcher deals damage to a selected target, it can cast a curse on it. The cursed creature does not benefit from a short and long rest, and after 1d10 + 3 days the soul of the creature will leave the body and be replaced by the essence of the Astral searcher who cast the curse. If a creature succeeds in a Saving Throw, it is immune to this skill for the next 24 hours.

The curse can be remove with the Remove curse spell or other similar spell. 

Blink. When an attack hits the Astral searcher, it can try to avoid the attack. A creature hit by an Astral searcher attack must throw the result and use the new result. If the attack misses after that, the Astral searcher teleports 10 feet away.