Ethereal Ancestor

You have some sort of connection to the Ethereal Plane, the realm of ghosts and mysterious ectoplasm. You may have gotten your connection when you were concieved while on the Ethereal Plane, or had an ancestor that was really a ghost possessing a body. Or it could be something as simple as your mother dying during childbirth. Either way, you can immerse yourselves in the Ethereal plane easier than most mortals, and you have a chilling presense. Your very physical form can look ethereal and terrifying, as startling as any true ghost.

Haunting Visage

Your ghostly ancestor granted you a haunting form just beneath your normal one. Starting at 1st level, you can use an action to show your ghostly form, cloaked in chilly ectoplasm. When you do, you gain the ability to see into the ethereal plane for 30 ft, and you gain advantage on Intimidation checks. You also gain advantage on Deception checks to pass yourself off as an actual ghost. You end this ghostly visage as a bonus action.

Also, you can attempt to frighten someone with your spectral face. Choose a creature within 30 ft. that can see you. That creature must succeed on a Wisdom saving throw equal to your spell save DC, or become frightened of you for one minute. At the end of each of the creature's turns, it can re-make this saving throw, ending the effect on a success Once you use this ability, you cannot do so again until you finish a short rest.

Phantom Step

Starting at 1st level, you can use an action at the start of your turn to become incorporeal, stepping lightly into the Ethereal Plane, passing through creatures and objects as if they were difficult terrain until the end of your turn. If you end your turn inside a creature or object, you take 2d10 force damage and are shunted to the nearest unoccupied space.

Once you use this ability in this way, you must finish a long rest before you do so again. Starting at 3rd level, you can spend 1 sorcery point (no action required) to regain one use of this feature.

Ethereal Cloak

You can weave chilly ectoplasm from the Ethereal Plane around yourself that shifts with the background. At 6th level, you can take the Hide action even when you would not be obscured or otherwise hidden. When you do so, you are considered heavily obscured. If you move more than half your respective speeds, or if you attack or cast a spell, this obscurement fades and you are no longer hidden.

You may use this ability a number of times equal to your Charisma modifier, regaining all uses upon completing a long rest.

Chilling Presence

Your very presence chills the air and your enemy's very hearts, and the air is noticeably colder around you to a radius of 10 feet. Starting at 14th level, any creature that enters your chilling aura or ends their turn there has their speed reduced by half and cannot take reactions until the end of their next turn.

Additionally, any elemental damage you deal can be made as cold damage instead.

Possession

At 18th level, one humanoid that you can see within 5 ft. of you must succeed on a Charisma saving throw equal to your spell save dc or be possessed by you; you then disappear, and the target is Incapacitated and loses control of its body. Your game Statistics are replaced by the Statistics of the creature though you retain your alignment and your Intelligence, Wisdom, and Charisma scores. Once you possess a creature's body, you control it, and you retain the benefit of your own class features. If the target has any class levels, you can't use any of its Class Features.

The possession lasts until the body drops to 0 hit points, you end it as a Bonus Action, you are turned or forced out by an effect like the remove curse spell, or 24 hours pass. The creature can re-make the saving throw if it takes damage, ending the effect on a success. When the possession ends, you reappear in an unoccupied space within 5 ft. of the body. The target is immune to this Possession for 24 hours after succeeding on the saving throw or after the possession ends. Once you use this ability, you must finish a long rest before you do so again.