Poison Drinker. The ghost is immune to poison damage. Any poison damage it would otherwise take is translated into restored hit points instead.

Incorporeal Nature. The ghost can see 60 feet into the Ethereal Plane when it is on the Material Plane, and vice versa. Furthermore, it has resistance to non-magical Bludgeoning, Piercing, and Slashing damage. Lastly, the ghost can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.

Magical Spectre. The ghost was created through a combination of curses and necromancy. It is an undead magical construct whose attacks count as magical for the purposes of overcoming damage resistances. Using the Remove Curse spell on it will vaporise it and allow its soul to pass on to the afterlife.

Spectral Touch. Melee Magic Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) necrotic damage. On hit, the target must succeed on a DC 12 CHA saving throw or become afflicted with a random d4 curse of (1) Blindness, (2) Deafness, (3) Enfeeblement, or (4) Necrotic Damage Vulnerability. Though the curses can stack, if the target succeeds on a subsequent repeat of the saving throw at the beginning of one of its turns, all curses are dispelled at once.

Ethereal Bolt. Ranged Magic Attack: +5 to hit, range 60/120 ft., one target. Hit: 6 (1d6 + 3) necrotic damage.

Minor Possession (Recharge 6). One humanoid that the ghost can see within 5 feet of it must succeed on a DC 12 CHA saving throw or be possessed by the ghost; the ghost then disappears, and the target is incapacitated and loses control of its body. The ghost now controls the body but doesn't deprive the target of awareness. The ghost can't be targeted by any attack, spell, or other effect, except ones that turn undead, and it retains its alignment, Intelligence, Wisdom, Charisma, and immunity to being charmed and frightened. It otherwise uses the possessed target's statistics, but doesn't gain access to the target's knowledge, class features, or proficiencies.

Whenever the possessed creature takes damage, its body makes a DC 12 CON saving throw. On a success, it is freed from the ghost's possession. On a failure, the possession continues as usual.

Typically, the possession lasts until the body drops to 0 hit points, the ghost ends it as a bonus action, or the ghost is turned or forced out by an effect like the dispel evil and good spell. When the possession ends, the ghost reappears in an unoccupied space within 5 feet of the body. The target is immune to this ghost's Possession for 24 hours after succeeding on the saving throw or after the possession ends.

Etherealness. The ghost enters the Ethereal Plane from the Material Plane, or vice versa. It is visible on the Material Plane while it is in the Border Ethereal, and vice versa, yet it can't affect or be affected by anything on the other plane.