you are a pile of dust.

This spell is missing a whole section of text.

A creature or object that makes a successful save is partially affected and takes half of damage. If this damage reduces the creature or object to 0 or fewer hit points, it is entirely disintegrated.

Quote from Nanan00 >>

This spell is missing a whole section of text.

A creature or object that makes a successful save is partially affected and takes half of damage. If this damage reduces the creature or object to 0 or fewer hit points, it is entirely disintegrated.

 That isn't "missing", it's omitted by design. On a successful save, nothing happens.

to be perfectly honest it is very vague on death, it states that they are turned to fine dust, but this doesn't exactly mean you are dead, so theoretically you could still roll death saves, and be a sentient pile of dust. You couldn't do anything until a true resurrection or wish spell is cast. but that is entirely up to the DM you are playing with. Also, why would you bring logic into a situation of magic?

"I'm playing as a level 12 pile of dust"

I know the spell states that only wish or true res can bring someone back from a disintegrate, but other than that, if you still have the ashes, is there a reason reincarnate wouldn't work? that spell says "You touch a dead humanoid or a piece of a dead humanoid" and the spell forms a new adult body, regardless of how small the piece was, so if you can re-incarnate someone from a toenail clipping, why not from a handful of dust?

no you are turned to dust its a instant kill

A brutal spell, and one of the best at killing things you want dead with wish. Remember, wish does not need to meet any requirements of a spell, including range. Meaning that a wizard can cast wish from anywhere in the universe (as other planes of existence mean nothing to the wish spell) and state “I wish to cast the disintegrate spell at 8th level against the one I know as my enemy.” And all of a sudden, without warning, that person or creature is naught but a pile of dust. 

"This spell automatically disintegrates a Large or smaller nonmagical object or a creation of magical force."

Does this mean that when it hits that "creation of magical force" and that creation is destroyed, so too is the disintegrate spell?

Disintegrate would destroy a Tiny Hut, and end the disintegrate,  from a caster from inside or outside of the Tiny Hut.

Wall of Force, which is an invisible, states that a Disintegrate will destroy it automatically. I would assume that the attempted victim, in this scenario, would be on the other side of the wall and thus protected from the Disintegrate. The Wall of Force is gone though.

If Disintegrate destroys (and ends) on creations of magical force, should the same rule apply to the Shield spell, which is "An invisible barrier of magical force" that appears and protects you? The mage would lose their shield spell, obviously, but be protected completely from the disintegrate.

What is the DC of the Dex Save?

It depends on the caster who is casting the spell.

Can you block this outright with a (magical) shield?

Quote from Yotaku_kun >>

What is the DC of the Dex Save?

The DC for the saving throw for any spell is: 8 + the caster's proficiency bonus + the caster's spellcasting ability modifier.

Quote from pokemonmasterdaley >>

Can you block this outright with a (magical) shield?

Shields increase your Armor Class, which makes it harder to hit you with attack rolls. This spell doesn't use an attack roll, so a shield generally wouldn't be helpful against it. Magic items improve Dexterity saving throws would help defend against it.

No.  You die.

Sleep is a pretty efficient method too.

Ok. Question. A creature has immunity to lvl 6 and lower spells. Would they take the potential damage if it were upcast with a level 7/8/9 spell slot?

I have a question. So it says that when you kill a creature: "A disintegrated creature and everything it is wearing and carrying, except magic items, are reduced to a pile of fine gray dust."

So, if you kill something that is huge with this, it all dissolves into dust. But if it dies by other means and you disintegrate the corpse, only a 10 foot cube of it gets disintegrated? Why is it different when it is alive? How could that be explained?