Phantasm

History

When a person dies, their soul travels through the material plane and into the ethereal plane. What happens after that, few know for sure. Some say they go meet the god they worshiped in life in the outer planes, some say their essence is broken down and repurposed into the building blocks of the ethereal plane. But what few know is that sometimes the soul does not leave the material plane at all. If someone dies without having accomplished a task that weighs extremely heavily on their soul, the soul itself can refuse to leave the material plane. If the soul’s determination to see their goals through is strong enough, that determination is enough to anchor the soul to the realm of the living, and that’s how what scholars of death refer to as a Phantasm is created.
Phantasms are physical manifestations of souls that refuse to leave the material plane on account of needing to accomplish a specific task. A Phantasm’s unfinished business is both what fuels their existence and what anchors them to the realm of the living.
Phantasms retain their memories and most of their personalities, but these do not make the transformation into undeath unscathed. Their unfinished goal takes over their psyche as the most important thing to them, and while they retain memories and a personality, these become secondary to their sole motivator: accomplishing their goal. A Phantasm might be able to laugh along with their companions while huddled around the fire, or listen as a friend shares their secrets, but a portion of their psyche is constantly fixated on the goal that ties them to this realm at all times. They are consumed by it, every waking moment a reminder that there’s a task that they need to accomplish -- and that they can’t afford to stray away from it this time, because there won’t be another chance to see their goal through.
Phantasms might look like people, but they are not true living beings, and this is perfectly exemplified by the most obvious physical attribute that all Phantasms possess. They have a perfectly circular hole in their chest. A reminder that their existence in the material plane is not a full existence, and that their souls won’t know peace until their goal is accomplished. This hole closes the closer a Phantasm is to accomplishing their goal, and widens the more they stray away from the goal they are meant to accomplish.
A Phantasm’s unlife ends in one of two ways. They may accomplish their goal, in which case the hole on their chest closes, and with it the anchor that ties them to the material plane. They can finally ascend, free of the constant weight of an unfinished task pressing down on their hollow soul. But if a Phantasm strays away from their goal, the hole in their chest grows until it swallows them completely. The soul cannot take the strain of tying them down to the material plane anymore, and under the pressure it simply breaks. The Phantasm and their soul are destroyed. No magical item, no ritual, no wish and no spell can bring them back, because there’s nothing left of them to save.
There have been accounts of Phantasms for ages. We know of knights who died before saving those they were sworn to and came back as ghostly protectors of the ones they pledged their lives -- and now unlives -- to. There are accounts of parents escaping war-torn countries arriving at an inn, their children sleeping in their arms. When they paid the innkeeper, they made him promise that the children would be taken care of, and once the innkeeper agreed the parents faded into nothingness, their goal having been finally accomplished. But we also hear of adventurers who refused to let their party be slaughtered at the hands of their foe, clinging to life and traveling together once more as Phantasms. There are even rumors of full adventuring parties of Phantasms, all sharing a single goal, refusing to give up until they see it through even if they died on their first try.

Phantasm Traits:

Creature Type: You are a Humanoid.
Age: The “lifespan” of phantasms is directly dependent on how quickly they accomplish or stray away from their goal. Their soul is constantly straining to keep them attached to the material plane in order for them to accomplish the goal that brought them back from death, so depending on the strength of their conviction they are able to remain for more or less time in the material realm.
Size: Your size is Medium or Small.
Speed: Your walking speed is 30 feet.
Darkvision: You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can't discern color in darkness, only shades of gray.
Incorporeal Nature: You are able to transition into an incorporeal state in which your body has the consistency of a smoking shadow. As a bonus action, you can make yourself amorphous and incorporeal, like smoke. Everything you are wearing or carrying is also incorporeal as long as it is on your person. While in this form, your movement is reduced by half, you have advantage on all Dexterity (Stealth) checks, attacks against you are made at disadvantage, you can’t be grappled and are immune to the prone condition, and you can move through a space as narrow as 1 inch without squeezing. You can maintain your incorporeal form for 1 minute, and you can end it early with a bonus action. If you make an attack or cast a spell you immediately return to your corporeal form. If you return to your corporeal form in a space that is too small to accommodate you, you are forcibly ejected to the nearest unoccupied space and take 5 (1d10) force damage per 5 feet traveled while being forcibly ejected. You can use this trait a number of times equal to your proficiency bonus, regaining all expended uses when you finish a long rest.
Ghostly Possession: You can temporarily detach your soul to control the movements of an object or someone else. As an action, you can target either a creature or an object that isn’t being worn or carried within 30 feet of you. Your DC for this ability is equal to 8 + your Wisdom modifier + your Proficiency Bonus. If targeting an object, you are able to either slowly move an object up to 15 feet, following whatever path you want it to follow, or launch it up to 30 feet in a straight line in a direction you choose before falling to the ground, stopping early if it impacts against a solid surface. If the object strikes a creature, that creature must make a Dexterity saving throw. On a failed save, the object stops moving and both the object and the creature take 3d8 bludgeoning damage. If targeting a creature, the creature must make a Wisdom saving throw. On a failed save, the creature must immediately move half its movement in a straight line in a direction you choose, provoking attacks of opportunity when moving in the designated direction. A creature can willingly fail their saving throw if they so choose. You can use this trait a number of times equal to your proficiency bonus, regaining all expended uses when you finish a long rest.
Undead Resilience: Your undead nature allows you to perform feats that those who still cling to life are unable to accomplish: You do not need to eat, drink, or breathe. You are immune to disease and have resistance against necrotic damage. You have advantage on death saving throws. You don’t need to sleep, and magic can’t put you to sleep. You can finish a long rest in 4 hours if you spend those hours in an inactive, motionless state, during which you retain consciousness. If you roll a 1 when spending a Hit Die when taking a short rest you can reroll that die. Additionally, if you complete a short rest and have no Hit Dice remaining, you regain 1 Hit Die.
Healing Resistance: The veil between life and death is so thin for you that magical healing is less effective when applied to you. When you receive healing from a spell that specifically states it has no effect on undead, you receive half the hit points healed, rounding up, instead of the full amount.