How is a soul different from the living creature that it came from?

Question

Short Version

If someone who can cast a spell like Plane Shift or Gate dies, what prevents their soul from simply casting the spell and returning to the Material Plane?

Explanation

From what I can tell, when a humanoid dies in the Pathfinder universe, he or she usually goes through this process:

1. Sometime after dying, his or her soul appears on the Ethereal Plane near the River of Souls.
2. Over some unspecified amount of time, the River of Souls carries the soul to Pharasma's Spire to be judged.
3. Pharasma judges the soul, usually sending them to an appropriate Outer Plane based on their alignment. The souls of PCs are usually held in the Boneyard until they can be raised from the dead.
4. Souls that pass on to the Outer Planes eventually become petitioners, losing their former abilities and their connect to their mortal body.

I can't find any information about how the soul is mechanically different from the original PC. However, the description of petitioners (including the Petitioner template) makes me think that until the soul becomes a petitioner, they're basically the same as the original creature. This seems consistent with other D&D-related media like Baldur's Gate and Order of the Stick, where the souls of the dead can retain class abilities and maybe even some gear.

If the soul is basically the same as the original creature and still has class abilities, what stops a caster from resting for 8 hours and then casting a spell like Plane Shift? How is this different from being brought back by Resurrection (other than saving 10,000gp)?

It Shouldn't Work, But...

To be clear, I'm not suggesting that this should work. As a GM, I don't think I'd let a player do this. I'm just trying to figure out why it doesn't work, to help me reason about souls, death, etc.

Ancillary Information

These are other pieces of information that I've found that may or may not be helpful in answering:

• Ghosts retain both their class abilities and incorporeal versions of their gear, though some other details change (e.g., creature type changes to undead).

Answer 1

They can, but there's a lot getting in the way of it.

The primary thing that stops most of them is that many souls are uninterested in returning to the world of the living as generally, their ultimate reward is greater than what they had while they were living.

But let's say that we have a very determined individual, one who probably wants to avoid their eternal punishment. In that case, they need to be a minimum of a level 9 cleric (10 for oracles), or level 13 Wizard (14 for Sorcerers), who also has Plane Shift known/prepared. The clerics, while being able to do it at the earliest levels, have their spells granted to them by their deity. This means they would have the hardest time of it, as they basically would need their gods permission to be able to Plane Shift away from the River of Souls. Most gods are unlikely to be OK with this, both because they would not like Pharasma to be angry with them, and because they want their followers to receive their final rewards.

The next issue is any material components, like a tuning fork that has been tuned to the Prime Material plane. When you die, only spiritual representations of your gear comes with you, and even then, usually only gear that was important to you.

After that, of course, is the fact that you're significantly more vulnerable as a soul with no body. Any Daemons that catch notice of you will gladly just straight up eat your soul entirely.

You also have to avoid the notice of the Phsychopomps, and there are three different types whose job is to explicitly find and bring back wayward souls trying to escape judgement.

• The Ahmuuth (CR4), who assist mortals in the destruction of undead and dispatching of souls trying to escape judgment.

• The Shoki (CR9) who hunt down lingering souls and trap them in their cold iron staves for transport back to the River of Souls

• The Morrigna (CR13), who act as bounty hunters and assassins, and seek out those who (like our would-be escapee) try to flout the natural cycle of death and judgement.

And if they can do all of the above, they still have almost no way to interact with the material world, being incorporeal and mostly powerless. Generally speaking, the few souls who meet even the first requirement are mostly unwilling to go through the effort required to come back to the Prime.

Answer 2

It's dead

Some spells that affect the dead will work on the soul of a slain creature differently than on the living creature. For example, deathwatch will register them as both dead and healthy, most likely.

It lacks duality

Much like an outsider, the soul of a dead humanoid doesn't have a body/soul duality. This means it doesn't leave (additional) remains behind to raise when killed in soul form, and that can make getting it back over to your party if it dies a second time a hassle (but, obviously, that's less of a problem if it's rocking e.g. plane shift and Well-Provisioned Adventurer(Arcane Adept)).

It is really hard to regain hit points

Dead characters have a lot of trouble regaining hit points and require special accommodations to do so. Specifically, "Dead characters cannot benefit from normal or magical healing" as part of the dead condition. That means only unusual mundane healing can restore hp to dead characters, such as via the fast healing special quality or the Treat Deadly Wounds use of the Heal skill.

Maybe other stuff

The above are just the notable RAW effects of being dead now. The main other effect I see happen on death in games is that a creature loses a level (or, in Pathfinder, gains a permanent negative level). RAW the level is lost when the creature is raised, not killed, but level loss on death instead being fixed by True Resurrection et. al. solves most of the problems by ensuring there is still a significant penalty to death. I've not ever seen a game where creatures are still tracked after death, yet don't lose a level when they die-- such a game would have to deal with infinite mage fights, for example, whereas with a level loss penalty characters have a reason to limit their investment in particular fights, and if they are exceedingly aggressive they may lose the ability to plane shift or otherwise quickly rejoin fights.

In most of the 3.x games I've played where this is a thing, plane shifting back in a round after death is reserved for Big-Deal combats, like final confrontations with the Big Bad or a seriously dedicated lieutenant, and even then most villains have enough sense to call it quits after the second or third time they die (at least once they off a PC just to have them pop back up as well, and then do the math). When they don't, the rapidly diminishing fight difficulty means that the GM usually summarizes the remainder of the fight rather than running it, and the players wait out, perma-kill (i.e. track down and kill below 0 Con), take prisoner, or negotiate surrender with the villain at more-or-less their discretion.

Pathfinder is a little different than 3.5 here-- the death penalty is negative levels, not real level loss-- but the situation is largely the same. Greater Restoration et. al. take at least a standard action to cast, generally, so using it before Plane Shift means you are giving the PCs multiple rounds to heal and buff before you rejoin the fight, and that's just not a tenable situation to be in. And, just like 3.x, if someone is annoying enough/breaks enough of the rules of war the offended parties will track that person down to their afterlife and just kill them over and over until they stop coming back, just in Pathfinder that's until their permanent negative levels exceed their Hit Dice and it's infinite-death-loop time.

Again, negative levels on death in Pathfinder is not a RAW thing, so this may not matter for your purposes.

Lastly, the process of death depends on campaign setting and might insta-petitioner you, for example, or otherwise prevent you from spellcasting after death. Like, your afterlife might be on a dead magic plane, for example.

Answer 3

Plane Shift problems

Like mentioned by others you would lack a body when you return and you only keep equipment that is important to you, so unless your character was overly attached to his material plane tuning fork...

A good alternative

would be dream travel. It does not have a focus component and gets you into the dimension of dreams, however it being a habitat for night and dreamthief hags could be dangerous. If you have the walking dream feat line, then you would be able to recreate your body with a dc 15-19 charisma check and create a tuning fork with a dc 10 or alternatively just have someone who would let you come back with them when they wake up.