These may not be kept up to date. We are using roll20 to play. We keep what rules we are using up to date there.
These rules are for souls not yet taken into a specific afterlife. If a soul has already been claimed and retrieved, then it may require entreating with an envoy of the deity in question or the deity herself. These rules might still be used to take a soul whom has been claimed, but there might be extra difficulties or story consequences.
The dead are taken along a river to the Sea of the Dead. In order to get the soul back you must both locate the correct soul in the Sea of the Dead (or the river if very recently deceased) and drag it up current back up the river to the material plane and the correct body.
The soul gains attachments to the Sea of the Dead. These are referred to as Soul Anchors. Each time a character dies she gains a Soul Anchor. The dead are loathe to leave the realm of the dead, even if the consciousness behind that soul does not understand exactly why they do not want to leave. The more often somebody dies, the stronger the urge to not return to the land of the living becomes.
There are three active parties involved with returning a soul to its body. The first is the caster. The second is the deceased. The third are assistants. There may be a fourth active party, but generally speaking deities and other higher being work through the participants that are present. Assistants must choose whether they will assist in finding the soul, or in returning the found soul to the body. Assistants must also be able to explain and possibly narrate how they are assisting.
The caster performs an Insight, Nature or Religion check. The DC is 8 +1 for every six hours the body has been dead up to twenty four hours (+4) with an additional +1 for every partial day after the first. There is an additional +1 to the DC for every Soul Anchor the deceased character has. Each additional character assisting in the search in a meaningful manner gives the caster a +1 bonus to the Insight, Nature, or Religion check. Any character involved in the search for the soul (caster, deceased, or assistants) may spend hero points on the roll. Assistants helping with bringing the soul back may also spend hero points on the roll. Hero points may be spent after the check is performed but before the DM rolls on the Soul Located table.
A successful Insight, Nature, or Religion check means the correct soul was located. Otherwise, the DM rolls secretly on the following table adding one for each Soul Anchor the deceased has…
Soul Located
d100 Effect
01–45 The correct soul is located.
46–60 The correct soul is not located. The caster is aware of the exact nature of the soul that was found instead.
61–75 The correct soul is not located. The caster is aware the incorrect soul was the one located.
76–99 The correct soul is not located. The caster thinks this is the correct soul.
100 The correct soul is forever out of reach without extreme direct divine intervention. The caster may think the incorrect soul was the one located and not be aware the soul is forever lost to being resurrected via magic available to mortals. It may be possible to embark on an adventure of some sort to find the soul.
After finding a soul, it must be returned to the body. The caster performs a DC 15 + 1 per Soul Anchor of the deceased ability check using the caster’s spellcasting ability modifier. Others may assist the caster with the task. Each additional character assisting in returning the soul to the body in a meaningful manner gives the caster a +1 bonus to the ability check. The caster rolls this. Any character involved in returning the soul to the body (caster, deceased, or assistants) may spend hero points on this roll. Assistants helping with locating the soul may also spend hero points on the roll. Hero points may be spent after the check is performed before the DM rolls on the table for the spell used if the check is failed.
A successful ability check means a soul is placed in the body. Otherwise, the DM rolls on one of the following tables depending on the means of resurrection…
Raise Dead
d100 Effect
01–40 The spell works as normal using the soul that was found.
41–60 The located soul isn't returned to the body, the spell slot and components are consumed, but future attempts are possible.
61–99 The deceased’s soul is irretrievable via magic available to mortals. The spell slot and components are consumed.
100 The located soul isn't returned to the body, the spell slot and components are consumed, but the soul isn't destroyed. In addition, a celestial or fiend of the DM’s choice instead inhabits the body of the deceased. The inhabitant must be removed from the body before the original creature may be returned to life.
Resurrection
d100 Effect
01–50 The spell works as normal using the soul that was found.
51–70 The located soul isn't returned to the body, the spell slot and components are consumed, but future attempts are possible.
71–99 The deceased’s soul is irretrievable via magic available to mortals. The spell slot and components are consumed.
100 The deceased’s soul isn't returned to the body, the spell slot and components are consumed, but the soul isn't destroyed. In addition, a celestial or fiend of the DM’s choice instead inhabits the body of the deceased. The inhabitant must be removed from the body before the original creature may be returned to life.
True Resurrection
d100 Effect
01–30 The spell works as normal using the correct soul even if a different soul was the one located.
31–60 The spell works as normal using the soul that was found.
61–80 The deceased’s soul isn't returned to the body, the spell slot and components are consumed, but future attempts are possible.
81–99 The deceased’s soul is irretrievable via magic available to mortals. The spell slot and components are consumed.
100 The deceased’s soul isn't returned to the body, the spell slot and components are consumed, but the soul isn't destroyed. In addition, a celestial or fiend of the DM’s choice instead inhabits the body of the deceased. The inhabitant must be removed from the body before the original creature may be returned to life.
It may be possible for the soul to still return to the body. Further casting attempts might be made unless the results from the table explicitly forbid it. Alternatively, perhaps a quest, calling in a hefty divine boon, or options such as the Revenant subrace from Unearthed Arcana may be possible. The exact means to return a soul that is irretrievable through the use of magic such as True Resurrection will vary greatly based on story options.
The tables for bringing an unclaimed soul back are based on, but not exact to those found on p53 of Xanathar’s Lost Notes to Everything Else. The rules for Fragile Souls found in Xanathar’s Lost Notes to Everything Else are similar to these and will likely serve most settings better than these rules do.
Various deities can pluck individuals out of the river on their way to the Sea of the Dead. Many but not all Afterlifes touch the River of the Dead if for no other reason than it is convenient. Particularly devout followers of a deity shine like a beacon to the collectors for their particular afterlife. A deity or her collectors may take an interest in any individual and attempt to retrieve them. A deity’s own followers are simply the easiest for her to locate. There has been more than one war to break out between two or more realms of the dead when their respective deities each wanted the same soul.