What happens to a Disintegrated Troll RAW?

Question

Related to This Question, and meant to provide a basis upon which that question can be answered.

Keep in mind that this is a Rules as Written question:

Questions about the rules as written are those which:

• Are investigating, as a priority, literal interpretations of the rules, even if they lead to absurd situations...

So, although this situation is absurd, it is a valid question by the site's parameters.

Trolls have the Regeneration trait:

Regeneration. The troll regains 10 hit points at the start of its turn. If the troll takes acid or fire damage, this trait doesn't function at the start of the troll's next turn. The troll dies only if it starts its turn with 0 hit points and doesn't regenerate.

This means that, if reduced to 0 HP, the troll automatically regenerates 10 HP at the start of its turn, only dying if Regeneration is overridden, via fire or acid damage.

The disintegrate spell description says:

A creature targeted by this spell must make a Dexterity saving throw. On a failed save, the target takes 10d6 + 40 force damage. If this damage reduces the target to 0 hit points, it is disintegrated.

A disintegrated creature and everything it is wearing and carrying, except magic items, are reduced to a pile of fine gray dust. The creature can be restored to life only by means of a true resurrection or a wish spell.

So, if we take both instances Rules as Written, this would mean that a Troll dropped to 0 HP would be disintegrated but not dead, because it

dies only if it starts its turn with 0 HP and doesn't regenerate

and

the target takes 10d6 + 40 force damage

and

The creature can be restored to life only by means of a true resurrection or a wish spell.

and because disintegrate deals force damage, not fire or acid damage, and thus the Troll is technically still able to regenerate, and thus doesn't die.

So what happens?

Of course, this breaks down into certain key points which must be considered in making a solid answer:

1. Does the ash regenerate?
2. Can it take actions?
3. Does it get a turn at all?
4. If any or all of the prior answers are no, isn't the troll basically dead?
5. What does this even look like in-game?
6. And how does this interact with the text, "...can be restored to life only by means of a true resurrection or wish spell", since the troll never technically died?

Answer 1

The troll turns into a dead pile of fine gray dust

The disintegrate spell reduces the troll to a pile of fine gray dust. The pile of fine gray dust is no longer a troll and therefore does not have the regeneration trait (for the same reason a troll polymorphed into a frog also does not have the regeneration trait). In case there was any doubt that the pile of fine gray dust is dead, Jeremy Crawford explicitly states that disintegration is death in this Sage Advice column:

If disintegrate reduces you to 0 hit points, you’re killed outright, as you turn to dust.

(Note: I believe that the troll's regeneration ability does not give it immunity to instant-kill effects, for the reasons outlined in this other answer, but the rationale I've given here for the specific case of death by disintegration is independent of that answer.)

Answer 2

Specific trumps general. Dead troll.

The Disintegrate rule says:

A disintegrated creature and everything it is wearing and carrying, except magic items, are reduced to a pile of fine gray dust. The creature can be restored to life only by means of a true resurrection or a wish spell.

It's reasonable to infer from "can be restored to life only by" that disintegrate means dead.

The text specifically calls out the "only" possible means of restoration: two rather high-level spells that are way above a troll's pay-grade. Troll regeneration is not on that list.

Answer 3

If this damage reduces the target to 0 hit points, it is disintegrated.

Nothing stops it from being reduced to 0 hit points. Nothing in the Trolls' rules prevent it from begin "disintegrated"... maybe. What does disintegrated mean?

Next, I'll assume this describes what disintegrated means:

A disintegrated creature and everything it is wearing and carrying, except magic items, are reduced to a pile of fine gray dust. The creature can be restored to life only by means of a true resurrection or a wish spell.

Disintegrated means the troll is now reduced to a pile of fine gray dust.

Now, there are three possibilities here.

1. Being turned into a fine gray dust kills you. In which case, the Troll is immune to this effect, as "disintegrated" or "being converted to fine gray dust" is not one of the conditions that can kill a Troll.

2. The Troll is converted, like a polymorph spell, into fine gray dust, and the Troll's game statistics are converted to that of Fine Gray Dust. As Fine Gray Dust is not alive, neither is the Troll. Somehow, despite the effect causing the Troll to be not-alive, the transition did not kill the Troll.

3. The Troll changes form to Fine Gray Dust, but otherwise remains a Troll. For most creatures, being converted to Fine Gray Dust is something that would kill you, and the next paragraph applies. Imagine if it read "ground into hamburger meat" instead of "fine gray dust"; something that would kill someone, but maybe not a Troll. And RAW says a Troll cannot be killed by being converted to Fine Gray Dust (as being Fine Gray Dust is not starting your turn with 0HP and being unable to regenerate). So at the start of its turn, it proceeds to regenerate 10 hp. It remains Fine Gray Dust, as nothing about the Regeneration grants it its mass or body back; strange, but we have the "Variant: Loathsome Limbs" rule. That rule has to do with the Troll losing limbs and how it gets them back: the Troll needs to spend a rest to get back limbs and heads.

Being dust means you don't have a head, arms or legs. So the Troll-dust has a speed of 0 and no attacks (from the lost limbs rules). It is also dust. Very tough, regenerating dust, but dust.

The dust blows away (or sits there), and after a short rest a Troll grows out of the dust. Because nothing is killing that Troll.

Answer 4

The troll lives.

Troll regeneration is very powerful:

The troll dies only if it starts its turn with 0 Hit Points and doesn't Regenerate.

1. Does the ash regenerate? Yes. It starts its turn at 0 HP but hasn't been hit with acid or fire, so it doesn't die, and instead regenerates.
2. Can it take actions? Yes. It's still alive and at 10 HP, so it's not Incapacitated.
3. Does it get a turn? Yes. Assume for a moment that it doesn't. Then it can't die, because it can die only at the start of its turn. Therefore it is still a living creature and keeps its place in the turn order. This contradicts the premise, so the premise is wrong.
4. Is the troll basically dead? No.
5. What does this even look like in-game?

I assume at this point it's not a RAW question? I'm thinking the troll turns to a cloud of ash, which instead of blowing away on the breeze or settling to the ground, solidifies into a troll, which then goes and murders the wizard.

6. How does this interact with disintegrate's restriction on restoring the creature to life? It doesn't. As you said, the troll never died. It just got disintegrated a little bit.