Ghost Knight

The chains holding your soul to your body loosen. You begin to slip from the Material Plane, able to access ethereal abilities and skills. Not quite a ghost, but not fully whole. You live somewhere in-between the world of the living and the world of the dead. Your body is now a shell, and you simply use it to interact with the physical world.

Possession

At 3rd level, you gain the ability to possess other creatures.

As an action, you can choose one creature that you can see within 5 feet of you. That creature must succeed on a Charisma saving throw or be possessed by you for one minute. The DC for the saving throw is 8 + your proficiency bonus + your Strength or Dexterity modifier. A creature whose CR or level is higher than your level automatically succeeds on this saving throw.

If you successfully possess a creature, you disappear, and the target is incapacitated and loses control of its body. You now control the body but can't deprive the target of awareness. You can't be targeted by any attack, spell, or other effect, except ones that turn undead, and you retain your alignment, Intelligence, Wisdom, Charisma. You otherwise uses the possessed target's statistics, but don't gain access to the possessed creature's knowledge, class features, or proficiencies.

The possession lasts until the body drops to 0 hit points, you end it as a bonus action, or you are forced out by an effect like the dispel evil and good spell or an ability that turns undead. When the possession ends, you reappear in an unoccupied space within 5 feet of the body. The creature is immune to this feature for 24 hours after succeeding on the saving throw or after the possession ends.

Once you use this feature to possess a creature, you cannot do so again until you finish a long rest.

Withering Weapons

Starting at 7th level, when you hit a creature with a weapon attack, you can deal an extra 1d6 necrotic damage.

This extra damage increases to 2d6 at 15th level.

Etherealness

At 10th level, you can use a bonus action to enter the Ethereal Plane from the Material Plane, or vice versa. You are visible on the Material Plane while in the Border Ethereal, and vice versa, but you can't affect or be affected by anything on the other plane. After 1 minute, or as a bonus action, you are teleported back to the plane you left.

You can use this feature a number of times equal to your proficiency bonus. You regain all expended uses when you finish a long rest.

Improved Possession

Starting at 10th level, creatures with a CR or level higher than your level only have advantage on saving throws against your Possession feature, rather than succeeding automatically.

In addition, posessing a humanoid does not expend your use of this feature, and you can target a humanoid with this feature even if it's already expended.

Improved Withering Weapons

Starting at 15th level, damage from your Withering Weapons feature increases to 2d6.

Incorporeal Mind

Starting at 15th level, your mind is so accustomed to being disassociated from your body that you become immune to the charmed and frightened conditions.

Master of Possession

Starting at 18th level, you may use your possession feature any number of times regardless of creature type.