THE HUMANOID SOUL
The soul of a Humanoid comprises three aspects. One aspect can exist as is a disembodied mind among the thoughts and dreams of the nonphysical Astral Plane. An other aspect is within the Material Plane, an aura of lifeforce that entangles a body. Additionally, a soul has a sense of self, comprising ones identity that one can be true to and self-express. This self is the aspect of the soul that bridges the mind and lifeforce aura.
The aura itself is immaterial lifeforce but entangles a body of matter, suffuses it and emanates outward from it. Usually the aura is subtle. Those who see auras, compare it to the flame of a candle, where ones material body is its wick from where light burns.
Sometimes, the influence of the rest of the soul can cause the halo to glow luminously, forming a halo around ones head and nimbus around rest of the body. For example, this visible aura happens during Psionic magic and while attuning Positive Energy, and generally results from the soul making a holistic extraordinar effort. Monk traditions call the personal lifeforce energy aura "ki" and guide it to produce various magical effects. The aura is also called an "animal soul" because, in the Material Plane, all Beasts of nature exhibit an aura. The aura aspect of a soul commingles the body and perceives via its senses and appetites. The aura anchors the rest of the soul within the Material Plane and helps orient the soul across the rest of the multiverse.
Separately, the mind is the aspect of the soul that is eternal. Monks call the mind the "Diamond Soul". This is the part of the soul that is indestructible. The mind is the only part of the soul that can exist in the Astral Plane. Actually, the mind is consciousness, thus is "no thing". It is like an infinite openness within which one can experience things, such as feel pain, pleasure, thoughts, sensations, love, memories, dreams, and other mental phenomena. But the consciousness itself is not any of these things. But rather, the conscious mind is the mysterious capacity to experience phenomena. The mind is no thing that can be destroyed.
The mind is nothingness. The information that a mind experiences is something else: the self. This self aspect of the soul is ones identity, ones nature, personality, musings, history, potential, fate, and choices.
The role of a "soul" in self-expression − such as in art, innate magic, being true to oneself, and intuition of a deep personal purpose − is the self.
The self aspect of the soul is the inner life of a creature. In some ways its characteristics are fixed and a creature is born with them "stamped" into ones self. For example, the gender of a character is an aspect of the self. Even the soul of a Warforged golem who lacks an anatomical biology can know ones self is a "man" or a "woman" or a being of an other gender, such as both or neither. Some Paladins know their soul came into the Material Plane to answer the "calling" to be a Paladin. In other ways, the self is the aspect of the soul that can learn and grow, and evolve with new experiences. The self is like a tree that springs from a seed. There is both continuity and change. To visit a new culture or embark on a new challenge or read new information from a scroll or perceive more deeply the perspectives of loved ones among friends and family, even strangers, can inspire the self to grow by new actions with new intentions to flourish in new ways. The influence of the self can expand beyond the Material body, across cultures and spaces and histories and times.
The three aspects of the soul are distinct levels. A lower aura of lifeforce among matter, an upper mind of consciousness among thoughts, and between them a self who lives an identity that informs both of the other levels.
MICROCOSM
A person of the Humanoid creature type is a microcosm of the multiverse. One soul is all worlds and potential worlds.
The physical body is made of the matter of the Material Plane. The aura of the soul entangles this matter for a lifeforce of the body, analogous to how gravity entangles the mass of a planet.
The self of the soul can discover new opportunities and imagine other versions of oneself. One can empathize from the subjective perspectives of other selves. Walk a mile in their shoes. Imagine other ways of being and carry out new ambitions. The self can multiply, do new patterns of actions, write new scrolls, interact with other persons, and exert spiritual influences beyond the limits of a body of matter. The actualizations of these intentions affect the spiritworlds within the Ethereal Plane, including the Border within the Material Plane itself, and Feywild and Shadowfell.
The "ether" of the Ethereal Plane is "spirit" as a substance. It is what Ethereal objects are made of. The ether is the Fifth Element, sometimes called "quintessence". Ether is a "force". Like gravity, it is immaterial and lacks the mass of matter. But like gravity, it is physical. It can push matter and form physical areas where its influence is strong. Force constructs are made out of ether.
The self is the part of the soul that is like a campfire on a hill at night that shines outward to be seen from horizon to horizon beyond the campsite itself. Via the ether, the self of a soul can extend outward beyond the material body − to move outofbody thru the world as an incorporeal physical presence. In this way, the self is the spirit of a Humanoid, who some call the ghost of a person. The Ethereal force of the self can manifest apparitions and produce other magical effects. It can also journey deep into the realms of ether where matter has little or no influence.
When a master swordsmith imbues the creation of a sword with owns own "soul" (compare the Japanese concept of "soul", "spirit", "self", "essence" tamashii), it is the Ethereal spiritual influences of the self that literally infuses the sword. Via the ether, the self of the soul exerts power elsewhere.
Both aura and self exert immaterial physical force. Both wield ether. The difference between aura and self resembles that between the Border Ethereal where the ether is part of the Material Plane like gravity, versus the Deep Ethereal where the ether is more responsive to the will of a persons intention.
The aura pervades the living body that is its sensorial perspective for the soul. By contrast, the self also includes concepts, intuitions, thoughts, and dreams that are a freeform perspective for the soul. The conscious mind can experience both perspectives, and often oscillates between them.
The Astral Plane is also immaterial, but even the force of ether is absent there. The "aster" is nonphysical. Its substance, sotospeak, is what thoughts and dreams are made out of. It is information, measurable in units of structures and transmissions. All that exists is made out of information. In the Astral Plane, this information is accessible. The mind subjectively experiences this information as a virtual reality, via its concepts, reasonings and feelings, paradigms and archetypes, and other semiotic constructs. The Astral Plane is sometimes called the "book of life" because it "records" all of the information that exists across space-time and the rest of the multiverse.
The Astral level of the soul, namely the mind, can engage from the perspectives of any of this informational aster but it isnt obvious at first. One must learn how to navigate it. One known idea can associate with an unknown idea. A mind can move from the edge of the known to explore the nearby unknown. Meanwhile the soul shares these virtual realities with other souls who are "nearby" within similar and associating informational perspectives. Some of this information is personal that an individual can innovate at a whim, other endures like patterns that an entire culture shares.
Where the soul resembles a candle flame, the wick is the body of matter itself. The fire around the wick that is often invisible is the aura. The bright flame around the aura is the self. Beyond the bright self is a subtle glow around the flame, that hints at the possibilities within the Astral Plane that a mind can explore.
MORE THAN THREE LEVELS OF A SOUL
The three levels of the soul are Material aura, Ethereal self, and Astral mind. There are even higher levels of the soul, but these are beyond any sense of a self.
For example, the mind is part of properties of consciousness itself, whence its interconnectedness of all things. This fourth level of the soul relates to events of Enlightenment, and is sometimes called the "no self", an awareness of the emptiness of oneself that is beyond and includes any particular self within it.
Ultimately a soul is utterly infinite, beyond the multiverse and any multiverses. This fifth level of ones soul is perhaps ones "true self", but the finite experiences of the self are unable to relate to it. This endless aspect might be what makes magic possible. In any case, each soul moves thru the worlds of the perspectives that it can and does experience.
While noting there is "more" to a soul, "beyond" what the finite information units of thoughts can articulate, it is common to refer to the Humanoid as having these three levels of the soul: aura, self, and mind.
THE SOULS OF CREATURE TYPES
Some creature types have a soul, but not all three levels of it. For example, the soul of an Angel is only a mind, whence the Celestial creature type. Likewise a Fiend is only a mind.
An Elf who is native to the Feywild has a soul with two levels: mind and self. Ultimately, the Elf mind originates from Corellon in the Astral dominion of Arvandor relating to the wider Chaotic Good thoughts called Arborea. The Elf self develops in the ether of the Feywild. It often looks to the Human species and other creatures and features of the Material Plane to inspire ways to be a self. With these two levels of the soul, the creature type is Fey.
By contrast, those Elves who employed magic to incarnate from the Feywild into a perspective of flesh and blood in the Material Plane, likewise have a soul that gains a third level, the aura. The creature type of these Elves is Humanoid with all three levels. They keep their "Fey Ancestry" whose mind and self share the characteristics of Fey Elves.
AFTERLIFE
At the death of a Humanoid, the aura remains in the Material Plane. But the mind becomes more free from the aura and its perspective, and eventually moves on to exist among the perspectives within the Astral Plane. The mind travels among the more familiar information constructs that the self has engaged while alive.
The mind starts off with a virtual body that resembles the moment of death. This continuity is important for the sense of self. Usually, this is while within the Material Plane while exerting Ethereal influence. A ghost. But soon with enough insight one can navigate to choose other relatable versions of oneself.
In this way, a disembodied mind clothes itself in a body of aster. The astral body is "virtual". It behaves according to the informational patterns that describe matter. The virtuality is like the material objects that one encounters during a dream. It feels solid, but one can shift from world to world, by walking thru a door way, or turning around a corner, or stepping thru a pool. The sense of distance is itself a concept. A mind tends to inhabit the informational possibilities that ones self generated while alive, tho perhaps less painful versions of it. Completely new experiences are also possible within the Astral Plane.
In the Astral afterlife, the soul maintains the connection to the corpse that it leaves behind in the Material Plane. The aura of ones soul continues to entangle it, albeit less vitally so. Despite the aura and the mind disconnecting from each other to function separately, the soul is both.
The identity of the self continues as an imprint stamped into the aura of the corpse, and also supplies the informational content that guides the mind to navigate the Astral Plane. Via the self, the soul bridges the lower Materal Plane and the upper Astral Plane. When loved ones visit the grave, the Astral mind can sense their bodies and auras interacting with the aura of ones corpse.
NECROMANCY
When necromancy animates a dormant Undead, such as a Skeleton, it manipulates the residue of the soul aura around the corpse. When interacting with a sapient Undead, such as with the spell Speak with Dead, it "awakens" the informational content imprinting in the aura of the corpse. The aura can transmit the record of any information that it knew while alive. This information is only as reliable as the soul used to be.
In all cases, the necromancy is harmless to the mind of the soul in the Astral Plane. The mind remains fully aware of any necromantic effects concerning the manipulation of ones aura.
It is rare and obscure, but certain things in D&D 5e can destroy a "soul". For example, a certain optional magic item, a sentient sword called Blackrazor, "devours" souls. Such soul-destroying effects can only affect the aura level of a soul. The mind level of the soul persists. The consciousness of a mind is eternal and cannot be destroyed in any way. And, it continues to navigate the informational perspectives of the Astral Plane. The mind is "no thing" to destroy. However without a bodily aura in the Material Plane to anchor the soul, the virtual Astral body of the mind can feel less stable. The information about the aura remains, but the soul loses the personal affinity with it.
HEALING ONES DEATH
Sometimes when referring to the concept of a "lost soul", this soul is without an aura to tether to the Material Plane to orient the soul from there. A Humanoid that loses the aura level of the soul ceases to be a "Humanoid" creature type. The aura level is gone.
Only a True Resurrection spell can restore such a former Humanoid, or else a riskful use of Wish. The magic recreates a replica of the material body and its aura in light of the Astral information, plus achieves a way for the soul to entangle it.
Sometimes the mind of the lost soul makes a great effort to incarnate into the Material World, to start over with a brand new life with a new aura and a fresh chance to nurture a new self. It is similar to the way some Elves chose to incarnate from the Feywild.
For a whole Humanoid soul that reincarnates, such as during a Reincarnate spell, the soul entangles a different body of matter, to form a new aura around it and a new self extending from it. The mind of the soul perceives from this perspective of the new body. Later when returning to the Astral Plane once again, the mind can share the informational perspectives of each body with its own aura and self simultaneously. Moreover, each incarnation often relates to an earlier one somehow, such as the soul returning to the Material Plane to complete a certain goal. There can be physical ethereal influences among these two or more bodies that relate to this context of a goal. The reincarnant can often sense ones other selves ethereally and recognize if coming across the remains of the bodily aura of ones earlier incarnation.
During a Resurrection, the mind returns subjectively from the Astral Plane to reunite with the aura of ones material body. The soul becomes whole. Yet the matter of the body has the peculiar property of shutting out the Astral Plane, and the mind of the soul typically only has a vague sense of having enjoyed the wondrous possibilities in the Astral Plane. The self that has already imprinted within the aura earlier is louder sotospeak than the self among the astral information. In other words, the resurrectant soul picks up where one left off while only "trailing the clouds of glory" from the Astral Plain.
During Revivify, the rest of the soul is still near the aura of the body, and restoring the body to living functionally is usually enough to graft the levels of the soul back together.
These restorations of a soul are examples where different parts of the soul separate and reunite.
JUDGMENT
The self that informs the mind guides its navigation within the Astral Plane to a familiar destination in the afterlife. Ones worldview that deeply mattered while alive now matters deeply in the afterlife. Ones ethical actions, loved ones, family and friends, and other ideals and devotions, persist vividly. A life well lived navigates easily. A life lived less ethically can bring their perspectives with them.
Among the Astral domains of the Evil alignments, a soul comes to be on the receiving of every Evil action they ever did while alive. It is ones own soul who judges oneself. There is no escape from ones own soul. In the Astral realms the information about ones own life lays out objectively. The mind subjectively becomes at the receiving end of every Evil action that the self ever did. One must experience every aspect of the harm, before becoming able to venture beyond it. The only way forward is thru. Even a self that did many Good compassionate actions can pass thru whole but not without pain. Their own compassion actions now turn around to assist them thru the struggle. A self that did many Evil things and only a single compassionate action would suffer almost the total loss of ones self. But at least that single compassionate action can survive, allowing some foothold of a self to persist. From there move on.
Eventually, the perspective of the self of the soul either gains a way to move on to other possibilities or else ceases to exist. Yet the possibility remains, if those who chose Evil while alive continue to cling to its cruelty, they potentially suffer for eternity. The Evil cannot pass thru. This purgatory that painfully "burns" away the Evil actions is sometimes called the "fire of Gehenna". All souls pass thru it in some sense, even if a few souls with an unusually high frequency of Good compassionate actions can arrive at the other side more whole and more quickly, to the Good information beyond.
SHADOWFELL
Sometimes when a Humanoid dies, ones soul refuses to leave the Material Plane. There can be many motives and is rarely about avoiding an Astral judgment. The motive is the Material Plane. This soul clings to the perspective of the dim aura of its corpse. It craves the physicality, even if only an ethereal and faint version of it. The perspective is the patterns of self identity that imprint within ones aura while alive. It perpetuates these same life experiences that it did while alive, over and over again, only this time without the possibility of a living body to make new life choices. These souls are of the physical world, except a fraught ethereal echo of it. The trauma of loss and the fear of the unknown obscures the perspective.
The Shadowfell is a collective grave where the ethereal influences of the aura of each corpse weave together. All corpses are here. All persons who die with corpses and auras are part of here. In the best case scenarios, a soul lingers for a bit of time, perhaps a week or a year, visiting loved ones and exploring curiosities while making sense of an end to a Material life. There is a Border Shadowfell sotospeak where each soul can "haunt" the places of ones life via the ethereal connections formed while alive. Eventually the mind chooses to move on, leaving the aura of ones soul behind.
The aura remains in the Shadowfell but typically "rests in peace" while the perspective of the mind is active elsewhere. The aura "sleeps". In the Shadowfell, all of these auras are the Undead creature type, and most are dormant. The Undead that stay active for many years tend to be the minds who refuse to leave. In a way they are no longer the Humanoid creature type, because they are only the aura level of their soul. Even their self level of the soul is "dead", inflexible, refusing to consider any possibilities beyond what their corpse recorded.
Because the light of the auras of dead bodies is dim, any perspectives of the minds here experience a faint ethereal echo of a life, with low energy and vague sensation. The ether looks gloomy and unraveling with abandon and disrepair. Eventually even these echos quite. A few among the Undead discover how to use the innate magic of ones soul to acquire more aural energy from elsewhere, such as the Vampire that "feeds" on life force directly from living souls. Others carry out the necromantic preparations that they made while alive. The auras of some Undead can be extraordinarily powerful to exert influence across the ether. Yet in other ways they are completely helpless and incapable of any personal growth beyond a corpse. Their apparitions are an intention to be in a way of things that no longer are.
Even among the souls whose minds find their way to the bliss in the Astral Plane, there is an awareness that their soul is unwhole. They leave a part of themselves elsewhere, literally. Even among an infinity of perfect worlds that they can discover or build within the aster, the one thing that they cannot have − the only thing they truly miss − is the opportunity to the make the Material Plane a better world. From their perspective they know. All the suffering they experienced while in the Material Plane is worth it, even if only to make it a little bit better.
THREE LEVELS OF THE SOUL
The "soul" is a technical term in D&D 5e that interacts with many rules and narratives. The above are a few examples with a sense of how they can cohere. It helps to understand, the soul is complex. It has at least three separable levels. Really, there is only a single infinite soul. But it somehow experiences subjectively from within the levels of the multiverse. A conscious mind exists among the thought and dream of the Astral Plane. An aura of life force entangles a physical body in the Material Plane. While alive, a self who grows and flourishes to exert influence across the Ethereal Plane, and whose identity informs the perspectives of both aura and mind.