In the campaign I'm playing, I've been given the option to choose between a Pearl of Power or Robe of Stars for my character (lvl 5 fallen aasimar divine soul sorcerer) and I'm trying to work out how short and long rests and recovering spell slots work, if at all, whilst in the Astral Plane using the Robe?

For example, mid-combat could I enter the Astral Plane take short/long rest, recovering charges/spell slots, and return back into the combat?

Oof. I guess you could make an argument for it based on the way time passes in the Astral Plane, but that has the potential for some considerable game-breaking repercussions if your DM goes for it. You could jump into the Astral Plane, take as much time as you like for downtime activities, then jump back into combat right where you left off. Alternatively, your DM might say that since time doesn't pass the same way in the Astral Plane and your body doesn't age, your body also may not naturally heal and recover and you might not benefit from a short or long rest while there.

Neither of those answers are entirely satisfying.

I agree with Texas, I think.Whenever I see an OP like this, my first instinct is "Stop trying to game the game, we're going to make it work reasonably in a way that avoids abuse in both directions." I am strongly against cheese. Here, I'd take that to mean creatures not aging =/= time not passing. Time still passes, you just don't age.

I would pick the Robe and I’d probably never use the Plane Shift ability. +1 to all saving throws and a few over powered a Magic Missile spells every day is more powerful than recovering one 3rd level spell slot a day. 

Quote from WolfOfTheBees >>

I am strongly against cheese. Here, I'd take that to mean creatures not aging =/= time not passing. Time still passes, you just don't age.

 

  This right here...  You take a long rest, you come back a long rest later in the Material Plane, combat will be over by then, one way or another.

Time passes normally in the Astral Plane and resting works the same.

If either worked differently the books would say so, but they don't.

Quote from Cyb3rM1nd >>

Time passes normally in the Astral Plane and resting works the same.

If either worked differently the books would say so, but they don't.

This. You could enter the astral plane mid-combat and take a short/long rest, but the combat would be long over by the time you return. The only weird time thing about the astral plane is that you don't age and don't need food/water while you're there. Time marches on at the same rate as on the material.

Thank you everyone for your replies. I didn't want to cheese or abuse the rules too much but was struggling to find clear rules on the subject. I do agree with Tim that even without the astral shift the Robe is a better choice over the Pearl.

I know this is an old conversation but I had to get involved. In the astral plane, yes, the time passes much slower. A thousand years would pass on the real world while you expirience only one or ten minutes. However, time passes slowly for your body too, meaning you won't get any benefit from long rest. So you maid the write call.

However, I wanted to ask, if anyone knows how do you gain spell slots back on the astral plane.

Time does not pass slower, the effects of time are different in the Astral Plane. If you spend 8 hours in the Astral Plane and then return to the Prime Material, 8 hours have passed in the Prime Material. However, while in the Astral Plane those 8 hours feel longer. Think of it this way - when you were in school and there were 5 minutes until the end of the day, did you ever stare at the clock and those 5 minutes felts like an eternity? That's what you feel in the Astral Plane. You regain spell slots in the Astral Plane the same way you do in the Prime Material. While you don't have to sleep while in the Astral Plane you can still sleep. If you could never long rest in the Astral Plane everyone would die of exhaustion. If you as a DM really don't like the idea of sleeping in the Astral Plane, you can re-flavor a long rest in the Astral Plane as 8 hours of light activity.

Not entirely true, I recommend you watch this video to see what I mean.

https://www.youtube.com/watch?v=gyGrsv9uOA0

The time does pass slower, this is why when you would drink a potion in the astral, the duration won't be an hour, because it lasts an hour in the material world but on the astral plane it would take a three hundred years.

Quote from DnDmentil >>

Not entirely true, I recommend you watch this video to see what I mean.

https://www.youtube.com/watch?v=gyGrsv9uOA0

The time does pass slower, this is why when you would drink a potion in the astral, the duration won't be an hour, because it lasts an hour in the material world but on the astral plane it would take a three hundred years.

I recommend you read the actual rulebooks instead of treating YouTube videos as official sources. Time passes the same on the Astral Plane as it does on the material plane.

MrRhexx is not a source of anything official or reliable. He pieces "lore" from multiple editions and makes up stuff too, trying to pass them off as a real answer. Many of videos include false information.

Information and lore changes between the editions. What was true in 3rd Edition, might be different in 5th, for example. You should only pay attention to the official books of the edition you're playing, if you want to present "official" lore. 

In official D&D 5th Edition materials time passes the same between Material Plane and the Astral Plane. 

I realize I'm incredibly late to the party on this one, but I stumbled across this thread while doing research on the Astral Plane, as my group was recently shunted there after a small extradimensional mix up.

One fact that is consistent through all editions, is that time flows at a normal rate on the Astral plane. In past editions, it went on to say that "a thousand years on the astral plane felt like only a day to the traveler." To this end, if anything, the Astral plane wouldn't be moving slower; by matter of perspective, only one day had passed, yet you had traveled about for a thousand years. I was curious so I did the math, and that equates to 4.2 days passing for every subjective second of experience. What feels like one turn in combat on the Astral plane, is in actuality 25.2 days.

Obviously, at the end of the day, it's up to the DM how it works and in what ways. Personally, that feels considerably more harsh than I'd like, so I scaled it back to one week of real time is one hour of subjective experience, which equates to a ratio of 168:1, as opposed to 365,000:1. After all, the Astral plane is a realm of dreams; and what are dreams, if not fleeting?

Old post, but I've been researching about this so I thought to add some snippets from the official books, also available here if you have the proper books from the virtual store:

"Creatures on the Astral Plane don’t age or suffer from hunger or thirst. For this reason, humanoids that live on the Astral Plane (such as the githyanki) establish outposts on other planes, often the Material Plane, so their children can grow to maturity."

5e Dungeon Master's Guide (page 47)

This does imply that bodily functions (such as growth, rest, potion effects and such) do not flow normally on the Astral Plane, regardless of how the time flows or not. It is worth noting that the githyanki have an specific kind of spell used when they're old enough to prevent time from catching up with them when they exit the Astral Plane (according to the books) in order to raid settlements on the Material Plane.

Regarding other editions, I was able to find the following quotes from 3.5e books: (I had to translate since my 3.5e books are in portuguese)

"The Astral Plane has the following characteristics:

• Gravity: Inexistent. Those that travel in plane move through thought (see more on the following pages). The objects and creatures without values of lnteligence can not move in the Astral Plane, although they can be pushed.

• Time: Timeless. Factors such as aging, hunger, thirst, poisoning and natural healing doesn't work in the Astral Plane, although those get back to normal as soon as the traveller leaves the Astral Plane."

"The Astral Plane has a timeless feature in relation to factors such as aging and disease, so a mage poisoned in this plane would not be affected until after it moves to another plane. A traveler in astral form simply would not be affected, since the damage suffered by the astral form is not transferred to the original body in another plane. The Astral Plane is also timeless in relation to natural healing, therefore only magic healing functions at that location."

3.5e Planar Handbook (pages 47 and 51)

There's smaller but similar quotes on the 3.5e Dungeon Master's Guide (page 152), even saying that the githyanki have no clerics on their race (due to how their society actually "prays" only for their lich-queen, named Vlaakith) and therefore they need to hire mercenary clerics for their ships since natural healing does not happen in the Astral Plane. This quotes from the 3.5e books lend to the understanding that recovering spell slots in the Astral Plane is not possible in the "natural way" (long rests) since the books explicitly say natural healing does not occur on the Astral Plane. By that logic, the idea of resting in the Astral Plane would not work regardless of how the DM would rule regarding the passage of time.

Unfortunately I do not have any books prior to 3.5e, so I can't check for quotes on previous editions.

It'd be up to your DM as the nature of the Astral Sea is somewhat arbitrary; certain things related to time and decay don't happen, but things do happen, so there is some form of passage of time there (otherwise nothing would work, you wouldn't be able to move etc.).

Since the Astral Sea in Spelljammer is now the main empty expanse of space, I'm personally inclined to rule that you can't long rest at all, as it will make the challenge of resource management a lot more pronounced. I might allow short rests for basic healing, arcane recovery etc., but might add some conditions to its use. It's also a good excuse to increase the value of the catnap spell as a way to trigger a short rest when you really need one.

According to the same books, yes you're right in regards to things happening. Things do happen, but as far as references in the source books, there's no hard definition to the rate at witch the time flows or not. However, there are rules forbidding natural healing and denoting the "timeless" nature of mundane things, such as poisons and potions. The books also have references as to say that time has not been properly experienced within the Astral Plane, but since those are refered as in-universe words, that would be up for debate.

However, I do need to point out that as a plane made specifically of thought and ether, time does not need to actually flow for the "translated astral forms" of creatures to move. The logic would be that movement would happen the same way dreams happen, beeing manifested through will and thought only, regardless of external factors. And since there's no real referential point between the experience of two different creatures within the Astral (since two different creatures inherently could move to the same location with different times of travel due to how travel in the Astral works), there's no real way of knowing for sure.

I believe it would be up to the DM how those time rates would work. Considering the effects of potions, poisons, hunger and such, I'd guess the most logical option would be to consider that time somehow flows slowly on the Astral Plane in relation to the Material Plane.

Considering the book references I would guess the most realiable way to regain spell slots would be to get a long rest within a demiplane, since according to the books the Astral Plane borders all other planes except those that explicitly state otherwise. However that would be somewhat risky due to the travel rules within the Astral Plane. One would need to be very careful to avoid loosing the previous progress of travel, if they're in between different destinations.

Your strategy with the catnap spell would also be a great way, as well as a more imediate one, delaying the need to reach another temporary plane to get a long rest.

Just recalled there's a reference both online and in some videos as to a place of research suposedly working on the subject of finding out the rate at witch time flows and matter decays within the Astral Plane, but I was not able to find any reference to that place on any official source books nor adventure books, so I'm not sure if that would be relevant lore-wise.

Its also worth noting that the Spelljammer book states that while things don't age in the Astral Sea, they do age normally in Wildspace since it overlaps both the Astral and the Material planes (or in other words, within the crystal spheres of any star system things age normally). Therefore you should be able to get a long rest within any section of Wildspace around any star system.

Given that long rests have absolutely nothing to do with age or whatever - long rests work exactly the same.

If you want variance in the actual passage of time relative to the material plane, I think the Feywild is your plane.