It's not clear that the ring would even activate
The operative part of the Ring of Mind Shielding's description is:
If you die while wearing the ring, your soul enters it, unless it already houses a soul.
However, the language used to describe the lich's abililty to reconstitute itself from its phylactery seems to carefully avoid the words "death", "...
Alright, this is going to delve into both canon and conjecture, as it must for such a nebulous topic. I'll break them down so we know which is which.
The Many Gods of the Dead
As has been noted (correctly), the Wall of the Faithless was established by Myrkul. His successor Cyric kept the Wall erected largely out of malice and sadism, never questioning its ...
There are several mentions of souls in the rules.
What we learn:
the soul can be separated from the body via Astral Projection (Astral Projection)
that the soul can leave the body without killing the body (Magic Jar)
that after death it continues to exist (Raise Dead, Resurrection, True Resurrection, Reincarnation)
that it is not always free to return ...
You can't have two Bobs at once, but that's not what you have here
If we look at spells such as reincarnate, raise dead, true resurrection, and resurrection, we see that they all mention the soul. However, the create undead spell does not impact the soul at all. To quote page 24 of the Dungeon Master's Guide "Bringing Back the Dead"
When a ...
Selling your soul doesn’t make you evil
Let’s not get into off-topic discussions about the nature of good and evil. Suffice it to say that being in debt to an evil demon doesn’t make you evil; only your own actions do that.
When does she get it?
To paraphrase an old Bon Jovi song: “I’ll live while I’m alive, and be in thrall to the Queen of the Spiderweb ...
Get a barghest to eat you1
This is probably the easiest solution, since barghest will attempt to consume goblinoid leaders. Simply pose as one using a spell like alter self and you can easily attract the attention of a barghest.
The section on the barghest in Volo's Guide to Monsters (p. 123) states
A barghest can feed on the corpse of a ...
The rules on this are not specific in D&D 5e, leaving it up to the DM.
There's no particular rule that says one needs an alignment to have a soul. In fact, Dungeon Master's Guide p.24, "Bringing Back the Dead", would imply that all living creatures have souls which depart upon death, as cited in the question:
When a creature dies, its soul departs ...
If the body was destroyed, the dragon's only real options are Wish and True Resurrection. All other revival and resurrection spells require a body.
The dragon can theoretically manipulate the player wielding the ring, but that's not really acquiring a new body.
The rules don’t define this. The absence of anything saying your soul goes anywhere might indicate that it stays where it is, though—in fact, the concept of selling souls isn’t explicitly mentioned in the warlock description at all. The only use of the word “soul” in the Classes section of the Player’s Handbook is for the monk’s Diamond Soul. Actually, ...
If the first contract has the price of the soul, the second contract cannot be entered into because the character no longer owns the soul and thus cannot sign it away.
Descent into Avernus (a published adventure) has the necessary rules for infernal contracts.
The contracts are described as:
A hallmark of devils is their delight in striking deals with ...
There Is No Rule
So it falls under a setting trope, but we'll come back to that.
In your first case, the character will return in the presence of the one doing the raising:
Revivify, raise dead, and resurrection require the caster to touch the body being raised.
When cast without the dead body, true resurrection creates a new one within ten feet of the ...
Maybe (a retroactively cast) Magic Jar and Glyph of Warding?
The Magic Jar spell (PHB, p. 257) enables a creature to send its soul into a prepared "gem, crystal, reliquary, or some
other ornamental container worth at least 500 gp": there's nothing in the text indicating it couldn't be a magical ring. While in that object, their soul can subsequently attempt ...
It varies by type of undead.
Each individual monster's description describes whether or not it retains its soul. This can include:
Souls without bodies: Some undead are souls. The ghost is a soul of a creature, bound to a specific place. The specter and will-o-wisp are corrupted souls.
Bodies without souls: Zombies are just bodies animated by necromancy or ...
The Classical Bargain
Traditionally (like, Goethe traditionally) the contract you sign with the devil gives you power while you live, and the devil gets your soul when you die. It's less of an immediate transaction where a radiant nebula drifts from your chest and into the sockets of an obsidian skull that bears a marked resemblance to you, screaming, now ...
Warlocks still have their souls within them
I know of no specific rules that say a Warlock's soul has been removed from their body or not, and D&D 5e has no secret rules. So off the bat the proper assumption should be that they have their souls.
But we can do better. There are various mechanics in the game that specify the removal of a soul, for which ...
The Wall of the Faithless was not actually made by Kelemvor, it was made by Myrkul.
I am not 100% certain how canon Neverwinter Nights 2 is for Forgotton Realms lore, but in that game, Myrkul claims he had constructed the Wall to dispose of unclaimed, faithless souls.
However, there could be multiple other reasons for him to do this. For starters, it is ...
The rules don't specify; revivify's limit is a good starting point
As with a lot of things, the D&D 5e rules leave a lot of latitude for interpretation. @Aviose came up with a good conceptual model in a comment on an answer to a question about souls in 2015.
I'm taking this opportunity to pull it out of a comment and put it into an answer that it fits. ...
Method 1: Have someone else raise them
Dungeon Master's Guide p.24, Bringing Back the Dead, suggests this exact course of action:
A soul can't be returned to life if it doesn't wish to be. A soul knows the name, alignment, and patron deity (if any) of the character attempting to revive it and might refuse to return on that basis. ... If the evil cleric ...
The Monster Manual answers this, explaining what you turn into based on where your soul goes. Being killed by a succubus doesn't change your destination, it's the fact that you have an evil soul that drags you down.
When the soul of an evil mortal sinks into the Nine Hells, it takes on
the physical form of a wretched lemure. (p67)
If you wish to become ...
All living creatures appear to have a soul.
According to Dungeon Master's Guide p.24, "Bringing Back the Dead":
When a creature dies, its soul departs its body, leaves the Material Plane, travels through the Astral Plane, and goes to abide on the plane where the creature's deity resides. If the creature didn't worship a deity, its soul departs to the ...
In 5th ed, there are a few mentions of souls, but there's no really comprehensive and mechanically-consistent metaphysics established. "Soul" isn't like "attunement," where it's mechanically defined whether or not something has it, and if not, how to get it. So regardless of anything else said here, it's going to have to be adjudicated ...
It's canonically ambiguous.
Like many of the big mysteries in Eberron, this question is left to the DM to decide. This type of intentional moral and cosmological ambiguity is a big part of the theme of the Eberron setting.
The people of Khorvaire consider the question of do warforged have souls? to be unsolved and controversial. The Eberron Races Unearthed ...
The soul can be free, but you need to find the body.
Almost all Spells that return a creature to life require a body(or part of a body). There is only one that specifically states it works without: true resurrection:
The spell can even provide a new body if the original no longer exists, in which case you must speak the creature's name.
Assuming you know ...
Welcome to Hell!
Actual lore and citations below
I want to preface that everything here is what I learned from reading Mordenkainen's Tome of Foes (MToF) and the Monster Manual (MM). I definitely recommend it as the story of the Blood War is absolutely fascinating plus you get to learn about how it could be extremely good or extremely bad for you if a True ...
If the target is evil, A Night Hag's Nightmare Haunting feature and Soul Bag might work.
While a hellfire weapon would send the soul to the Styx, that might not get them to Dis. However, if the target is evil, there may be another option.
According to the description of a Night Hag's Nightmare Haunting feature in MM pg 178:
If this effect reduces the ...
It is canonically undefined
In published 5e lore, the only mention of a warforged soul is in the introduction to the race:
“Pierce was built by design, while you were built by accident,” Lakashtai said. “The soul is what matters, not the shape of the vessel.”
“What makes you think he has a soul?” Gerrion said.
“What makes you think you do?”
— Keith Baker, ...
The soul knows the body before it chooses to enter it
The reincarnate spell states:
You touch a dead humanoid or a piece of a dead humanoid. Provided that the creature has been dead no longer than 10 days, the spell forms a new adult body for it and then calls the soul to enter that body. If the target's soul isn't free or willing to do so, the spell ...
It doesn't say
Because the spell doesn't say, there really isn't a way to answer this either way and it becomes up to the table/DM to determine.
You can look at the argument of "it doesn't say it does, so it doesn't" or you can say "it makes sense to me that it does, so it will."
Resurrection becomes impossible after this event
Note what is said on page 7 of the adventure, under "Soul Devouring":
This is very clear. Nothing, not even Wish or Divine Intervention will help in this situation.
Awaken does not confer a soul, since spells do only what they say they do. Inferring from several things said in the rules, though, the game assumes living creatures already have a soul by default, which is why creatures like the ones you mention - zombies, golems and simulacra - must specifically be called out as not possessing a soul.
I base this on the ...