Ancient Banshee

Detect Life. The banshee can magically sense the presence of creatures up to 5 miles away that aren’t undead or constructs. She knows the general direction they’re in but not their exact locations.

Incorporeal Movement. The banshee can move through other creatures and objects as if they were difficult terrain. She takes 5 (1d10) force damage if she ends her turn inside an object.

Multiattack. The Banshee makes a Curse and two attacks: one Corrupting Touch and one Ghost Bolt.

Curse: One creature the Banshee can see within 60ft must make a DC 15 Charisma Saving Throw or have disadvantage on their next attack rolls.

Corrupting Touch. Melee Spell Attack: +4 to hit, reach 5 ft., one target. Hit: 12 (3d6 + 2) necrotic damage.

Ghost Bolt. Ranged Spell Attack: +5 to hit, range 60/120, one target. Hit: 11(2d10) necrotic damage

Horrifying Visage. Each non-undead creature within 60 feet of the banshee that can see her must succeed on a DC 15 Wisdom saving throw or be frightened for 1 minute. A frightened target can repeat the saving throw at the end of each of its turns, with disadvantage if the banshee is within line of sight, ending the effect on itself on a success. If a target’s saving throw is successful or the effect ends for it, the target is immune to the banshee’s Horrifying Visage for the next 24 hours.

Possession (Recharge 6): One humanoid that the Banshee can see within 5 ft. of it must succeed on a DC 15 Charisma saving throw or be possessed by the Banshee. The Banshee now controls the body but doesn't deprive the target of awareness. The possession lasts until the body drops to 0 Hit Points, the Banshee ends it as a Bonus Action, or the Banshee is turned or forced out by an effect like the Dispel Evil and Good spell. When the possession ends, the target is immune to this Banshee's Possession for 24 hours after succeeding on the saving throw or after the possession ends.

Wail (1/Day). The banshee releases a mournful wail, provided that she isn’t in sunlight. This wail has no effect on constructs and undead. All other creatures within 30 feet of her that can hear her must make a DC 15 Constitution saving throw. On a failure, a creature drops to 0 hit points. On a success, a creature takes 10 (3d6) psychic damage.