Possessed
Mr.Knightson headed to the old mansion to investigate the incident that had been reported that day. He seemed exhausted when he came out, and bumbled around, swinging his cane like a grumpy old aristocrat. Frankly, I'm not sure if "Mr.Knightson" made out of that mansion at all.
Spirits in New Bodies
The true identity of a possessed is a subject of debate. When a spirit inhabits a body, and takes full command of it, are they the spirit or the body which they inhabit?
The only truth is that whether bound by force or by some manner of contract or agreement, the two sides of a possessed always wrestle for control. Nonetheless, a possessed isn't simply someone being puppetteered, but rather a spirit which becomes one with someone else's body. They do share that body's sensations, and memories may sometimes leak to one spirit or the other within the body.
One Kind, Many Shapes
There are several types of possessors, from simple wandering spirits to cursed artifacts. However, they tend to have a goal or a regret that keeps them attached to the material plane, and rarely one they can so easily accomplish. As such, many possessors get a glimpse of eternity as they cycle through body after body.
Parasytes
It is not surprise that the possessed are viewed as paraysites and those who host them. Often, even after free from a spirit's influence, the host may yet be shunned for what they may still be hiding within them.
Possessed Traits
With the personality and the power of a spirit within you come several benefits.
Ability Score Increase. Your intelligence score increases by 2, and one other ability score of your choice increases by 1.
Age. The possessing spirit does not age, and they stop the aging of the body which they possess.
Alignment. The possessing spirits tend to be uncaring of the life they are taking over, making them typically evil.
Size. Your size matches that of your parent race.
Speed Your base walking speed is 30 ft.
Languages. You know common and two other languages of your choice.
Malignant Occupant. You are vulnerable to radiant damage. In addition, whenever you take radiant damage, or when another attempts to exorcise you with a legitimate method, you must make a wisdom saving throw with a DC of 13 minus your proficiency bonus. On a failed save, the host's mind takes back control. You can repeat the save every hour assuming you haven't been expelled from the body.
Just a Vessel. You are capable of pushing the body you inhabit beyond its natural limits. You are proficient with constitution saving throws and if you would drop to 0 hit points or less without being outright killed, you may instead choose to drop to 1 hit point. If you do, you are considered undead and may not use this feature again until you complete a long rest.
Then, make a constitution saving throw with a DC of 10+Half the points you would drop below zero, rounded up. On a failed save, you take a level of exhaustion.
Spirit Within. You can sense and communicate with any undead within 20 feet of you, even if that undead would typically lack the intelligence required to understand a conversation. Starting from 3rd level, you may cast the Puppet spell once using this feature, and may not do so again until you finish a long rest.
Eldritch Advance. When you take the dash action, instead of doubling your movement you may opt to gain the ability to move up, down, and across vertical surfaces and upside down along ceilings, while leaving your hands free. You also gain a climbing and crawling speed equal to your walking speed. You don’t loose half your movement from difficult terrain and you may use the dash action even if you were knocked prone.
The original possessor may come in many different shapes, and should they be separated from the possessed body, it might be necessary to know what it is. Here are a couple suggestions:
Spirit. You are a ghost with unfinished business in the material plane and who needs a physical medium to interact with it. Choose now, one regret, target of vengeance, or unfulfilled oath.
Upon being separated from your host, you become a creature with the statistics of a ghost, except you do not have any of its action traits. You may escape or attempt to possess a new (or your old) host immediately by having them roll a wisdom saving throw against your charisma score. You may not attempt to possess someone you failed to possess, or if you were exorcised with your host still alive less than a day ago. If the target of your attachment is within sight, you may blindly unleash the typical ghost actions until you have fulfilled your desire, after which you disappear for good.
Object. Choose one non-magical object no larger than a set of clothes. This object is now considered magical (these magical weapons are not magical for purposes of overcoming resistance) and becomes indestructible except to blessed weapons. You were a spirit sealed within an object, or perhaps a curse spawned from the object itself, and take possession when you are worn, wielded or equivalent.
You can tempt people to use you, possess them, or make them give up on removing you, with a wisdom saving throw against your charisma score as a DC. You cannot take any actions aside from this, nor can you move or speak, as the object, though you can sense the world around you through sight and sound.
Eldritch Spawn. You were a being spawned from other plane or a simple unknown. Choose a number of signs that mark your possessed as taken over by the eldritch being. If you are separated from your host, you decide to leave a small mark on one random witness. Every night for a year, you can attempt to convince them to become your new host with any of your charisma skills against a wisdom save from them. If you fail to, you disappear back to where you came from.
Variant: Alter Ego
Instead of being under the control of a foreign entity, perhaps you are instead taken over by a different side of yourself, by losing control over some of yourself or perhaps through a method that induces the emergence of a different personality.
If you pick this variant, the usual Possessed traits (except for speed, size and languages) are replaced with the following:
Ability Score Increase. Your strength score increases by 2, and one other ability score of your choice increases by 1.
Age. You age and mature as the same rate of your parent species.
Alignment. Alter Ego's don't tend to a particular alignment, except that they are always the opposite of their original selves in some way. If the original self was true neutral, then they must choose a non-neutral alignment.
Malignant Transfiguration. Select one method of transformation. This method must either take at least one hour to perform, or it must be something over which you do not have control. Using this method, you may switch between the two selves which govern your body. You can choose whether either shares memories of what happened while they were the other. At any time, you may tempt your original self to transform by having them roll a wisdom save against your charisma score, with disadvantage if they are asleep. However, whenever you attempt to perform an action that would be against your original self's alignment, your GM may have them perform a wisdom save against your charisma score, and if they succeed you loose control to that personality.
One Body, Two Trades. Select one of your skills you are proficient in, and one skill in which you are not proficient. When you switch back to your original self, that skill is replaced with the other skill. If you would gain a double proficiency bonus on that skill from any means, you gain it for the new skill instead.
While I sleep, They Live. You do not need sleep so long as none of your selves stay awake for longer than 16 hours in a row. If you would be put to sleep by magical means, instead you switch selves, unless both selves are put to sleep. You may spend long rests as the self you switched to if you occupy yourself with only light activity.
Just a Vessel. You are capable of pushing the body you inhabit beyond its natural limits. You are proficient with constitution saving throws and if you would drop to 0 hit points or less without being outright killed, you may instead choose to drop to 1 hit point. If you do, you are considered undead and may not use this feature again until you complete a long rest.
Then, make a constitution saving throw with a DC of 10+Half the points you would drop below zero, rounded up. On a failed save, you take a level of exhaustion.
Eldritch Advance. When you take the dash action, instead of doubling your movement you may opt to gain the ability to move up, down, and across vertical surfaces and upside down along ceilings, while leaving your hands free. You also gain a climbing and crawling speed equal to your walking speed. You don’t loose half your movement from difficult terrain and you may use the dash action even if you were knocked prone.