My players did a stupid and I'm lacking ideas for next session!

[Mojake]

My players are currently in a Duergar stronghold. They entered through a secret tunnel to save some Dwarven allies and succeeded in freeing half of them, and killing 6 Duergar guards over 3 encounters (my party of four are all level 3).

The issue is that I gave my players a time limit of 6 hours before the prisoners were put on work rotation and the guards were changed, but after these 3 encounters they have retreated to a "safe-spot" for a long rest.

During their sleep, the Duergar will discover that the 4 prisoners have escaped and that 6 Duergar were killed, and will definitely take action. The Dwarves were exhausted, unarmed and ball-n-chained so I don't think the prison break conclusion is believable.

Their plan next session is to just head back in to save the other 4 Dwarves through a network of secret tunnels they found out about (which requires journeying back the way they came - where they killed previous guard patrols).



Personally, I think that these ruthless Duergar would follow the trail of corpses back to their resting spot and ambush them in their sleep. Is this fair of me to do? It would lead to them being killed or captured (the more likely option), and would also probably conclude with the Ranger's Animal Companion being slaughtered instead of being enslaved for mining etc.

Is there another way? What else could happen? How can I make a prison escape more interesting? Help?! I really didn't expect them to just go to sleep without hiding the bodies or covering their tracks! :smallsigh:

[Newtonyd]

Could one of the dwarves they already rescued be exceptionally brave and come back in to help the players rescue the rest after making sure the first group made their way to safety? The dwarf would know the duergar guards' rotation, since they'd been imprisoned for so long, and would know the players will be discovered soon.

[Mojake]

The 4 Dwarves they rescued are still with them and resting with them, as there's no simple way out of the dungeon. The Dwarves will each have 2 levels of exhaustion (3 if the long rest is interrupted) and have little to no equipment... They'll be pretty useless.

[Segev]

Have you...reminded the players about the six hour time limit? They may have forgotten, OOC. IC, there's little chance they would have; their lives and mission are on the line.

[sophontteks]

You can always use the infamous "Are you sure?" When they are doing something foolish.

But, yeah, they can't just long rest when its conveient to them. Sure, they burned their abilities, but they are still in danger. You make it sound like they have taken little action to actually evade their persuers or hide their trail. Some lessons are tough, but you want to set the precedent right away. You can't just call timeout after a jailbreak to get your abilities back. A short rest is an entirely different story.

You can have a smaller scouting party up ahead that may give the larger force away. Give them a chance to run if they notice. You can also ex machina it a bit where something actually wakes them ahead of time and warns them. Either case sets up a chase encounter. More dwarves will probably die, since they are exhausted.

[Mojake]

I dropped a bunch of hints (subtle ways of saying "are you sure?", "you backtrack through the caves, passing the bodies of fallen foes", etc.). The weird thing is that they came up with ideas when they first dispatched the Duergar, but never followed through with them; such as making it look like a Grimlock attack. I just feel like they really messed up here. We play for 4 hours on a Tuesday evening (after 3/5 of us have a busy workday) so I can't even attribute it to the whole group being too tired to realise...

True, they cannot just get away with a long rest. The scouting group idea is good, I could make it somewhere in the region of 8 misc. Duergar; with the implication that there are multiple scouting groups scouring the cave complex.

[Sol]

The rules for interrupting a long rest are as follows: a total interruption of longer than 1 hour invalidates the rest. Participants of a long rest may spend 59 minutes and 59 seconds over the course of the rest in intense combat, or sprinting laps, or weightlifting, or being waterboarded.

The penalty for your long rest being interrupted for more than 1 hour is that you must then start counting again, if you wish to immediately try again. A character may only benefit from one long rest in a 24 hour period -- but if a long rest was interrupted to the point of invalidation, they have not benefitted from one, and may re-try at any time.

So, among other options, they could spend the first 45 or 50 minutes of their "long rest" backtracking and searching for a more secure/hidden location. It sounds from your description like they're in a "secret" series of tunnels, so there's probably well-hidden locations in these tunnels. Even if they do get found by a search party, 5 rounds of combat is 30 seconds.

If they left a trail of bodies leading into the tunnels, the Duergar will absolutely send search parties, but if there's enough tunnels, these search parties could be small enough to be non-unavoidably-lethal.

Best policy here? Discuss with your players openly the odds of a search party finding them, and roughly the size of the search parties that are likely to be sent into the various tunnels, with the better hidden locations having a better chance to avoid or have a smaller party.

Then roll dice. Either separate dice for "being found" and "search party size", or just a percentile die with tiers for whatever outcomes you agree are likely.

Discussing these odds openly with your players is an easy way of simultaneously indicating to them that they may be making a dire mistake, without you having to outright say, "don't rest now or you're probably all going to die." It's highly likely that they are making the decision to rest because they feel that if they don't rest now, they're going to die. Be careful that you don't make this feel like an un-winnable situation with no solution and that they're likely to die either way. I've been in plenty of games where every encounter is harder than it should be and there's insufficient opportunities to rest. Some people enjoy hardcore difficulty level. Most people honestly don't.

Ask yourself what the correct thing for them to be doing actually is. Did their earlier combats against the guards go particularly poorly for them? Do they legitimately need this rest or they risk death?

[DeTess]

Are these new players? Or at least players new to your DM style? If so, it might be worthwhile to drop a very unsubtle hint. Either flat out tell them 'if you rest here and now, your mission is going to fail and you're going to die because of these reasons', or drop the hammer you think needs to realistically be dropped, and then rewind. They won't make that mistake again.

You think you might have made this clear already, but you need to understand that pc's are really stupid. They might be really smart people irl, and positively devious dm's, but the moment a character sheet is put in front of them, iq drops by an average of 30 points. This is a scientific fact.

[Mojake]

They have already begun the rest, so a backtrack can't happen. I don't believe that they needed the rest; they all had most of their HP intact, a couple of spell slots remaining, healing potions and the Druid had a single Wild Shape left.

They are not new to my style of DMing, 1 of them I've been DMing for for 3 years, another for 2 years, and the other 2 this is their first campaign under me. Only one of them is a new player. We are 30-35 hours into my campaign. Annoyingly, they acknowledged the bodies themselves and acknowledged their time limit, yet they still chose to long rest. I think they need to feel the hurt for their mistake.

[Segev]

I dropped a bunch of hints (subtle ways of saying "are you sure?", "you backtrack through the caves, passing the bodies of fallen foes", etc.). The weird thing is that they came up with ideas when they first dispatched the Duergar, but never followed through with them; such as making it look like a Grimlock attack. I just feel like they really messed up here. We play for 4 hours on a Tuesday evening (after 3/5 of us have a busy workday) so I can't even attribute it to the whole group being too tired to realise...

True, they cannot just get away with a long rest. The scouting group idea is good, I could make it somewhere in the region of 8 misc. Duergar; with the implication that there are multiple scouting groups scouring the cave complex.
Personally, I think you should have reminded them of these ideas. It sounds like the PLAYERS needed the mental break, because they forgot their plans and important details.

When the players are doing something blatantly stupid, it's usually because they are not physically present in their PCs' positions in the world. They're missing something. Especially if the players said what they wanted to do, and now don't seem to be remembering it, I think it time to start the session with an OOC reminder.


They have already begun the rest, so a backtrack can't happen. I don't believe that they needed the rest; they all had most of their HP intact, a couple of spell slots remaining, healing potions and the Druid had a single Wild Shape left.

They are not new to my style of DMing, 1 of them I've been DMing for for 3 years, another for 2 years, and the other 2 this is their first campaign under me. Only one of them is a new player. We are 30-35 hours into my campaign. Annoyingly, they acknowledged the bodies themselves and acknowledged their time limit, yet they still chose to long rest. I think they need to feel the hurt for their mistake.

You can ALWAYS backtrack. Nothing of import, by definition, has happened between their choice to long rest and the long rest being partway done. I think you should remind the players of their original plan, and of the time limit, and ask if they still want to be doing that short rest. If not, restart next session back at the point where they left off to take a rest, rather than with them mid- or post-long rest.

[eternall newbie]

Go with your plan and let the cards fall as they may, I mean without TPKing the entire party, which is what would probably happen in this scenario. I hope/assume they at least put a watch. Maybe have one enemy scout come at them and if they can take him out quickly and quietly they can at least buy some time to plan what to do next.

[solidork]

You've even got some NPCs there be like "Won't the Duergar find their dead friends and come looking for us?"

[DMThac0]

Reading into this, looking at your rebuttals, and taking my DMing style into play here I would do this:

Open with a brief summary of the end of the previous session.

End with them taking the rest and prompt them with a "faulty memory" moment and ask "Were you taking a long or short rest?"

If they confirm a long rest, have them set upon by the Duregar scouting party. If they're near enough, have them hear the alarms raised. Set up a much stronger defensive position of the Duregar camp. Let the chips fall.

If they confirm a short rest, give them the short rest. Set up the Duregar scouting party, alarms and defensive actions. If they take too long after the short rest...game on.

[Thrudd]

It depends. If you think you already made the situation clear and they should know better, then just play it straight and let the consequences play out as they will. If they are new to RPGs and might not be used to thinking strategically/holistically about their characters' experience, then be lenient. When you start the next session, remind them of what is going to happen in six hours, give them a hint that this might be a bad idea, and give them an opportunity to rewind and choose a different course of action that considers all the factors.

Your overall ideas seem perfectly reasonable - All you need to do is decide the schedule and behavior of the Duergar and from that can easily decide what they would reasonably do upon finding dead guards and escaped prisoners. Think it through step by step and come up with a time line, and add some random chance into the proceedings when the Duergar have choices to make.

First step - do new guards come to relieve the ones who are dead? How many come?
When they get there, what will they do? Are there alarms signals like bells that they ring? Do they have to run back and tell someone?
If there is no general alarm system in place, will they decide to investigate on their own first, or run to get help, or send one person to get help while others investigate? That might be the first thing you can roll to decide - if the guard replacements choose to hunt for the prisoners themselves or send for help, or both.
If someone runs for help, how long does it take to get where they're going and how long for the hunting party to get together and come back? How many Duergar can be spared to look for prisoners (probably should figure out how many fighting-capable Duergar there are in total if you haven't already and what their roles are), and what will they do with the other prisoners while they are hunting?

When they find the dead bodies, how will they figure out where the PCs and prisoners went? Do they have trackers? Is the path so obvious that they don't even need trackers to find them? Would they need a ranger or something (some kind of dogs or sniffing underdark animal) to track the prisoners? In any case, this is possibly where more rolls come into play - do they immediately find the trail of the escapees? Do they go in the wrong direction looking for them? Roll for it.
How long does it take them to find the hiding spot (if it is, in fact, a hiding spot and not just camped out in the middle of a passageway)? Roll for it. Maybe the players luck out, and it takes long enough that they finish their rest. Maybe not.

Do the Duergar move silently and stealthily on their hunt, or do they have multiple groups of hunters shouting to each other and stomping all over the place? If they're trying to be stealthy, that's another thing you roll for. Will the party's watchman hear or see the hunters coming before it's too late, or will they get ambushed? If they see them coming far enough in advance, can the party run for it before getting into a fight?

[Unoriginal]

Personally, I think that these ruthless Duergar would follow the trail of corpses back to their resting spot and ambush them in their sleep. Is this fair of me to do? It would lead to them being killed or captured (the more likely option), and would also probably conclude with the Ranger's Animal Companion being slaughtered instead of being enslaved for mining etc.

I'd offer the players to retcon what they did at the end of last session if they genuinely forgot about the issue (the characters aren't that likely to forget, after all), but if they don't want that, sure, what you says here seem the most logical outcome.

[urandom]

I would say give the Duergar a survival check or two to track the party back (opposed by group stealth check perhaps).

Then give party perception check (assuming they have a watch) to hear the duergar scouts (high dc), or approaching war band (lower dc). If they hear them, then they get to try to run away in the night without getting caught (not easy, but possible). If not, then they get ambushed in the night, and are probably captured and enslaved. Then I'd see what they do. Player's can think themselves into dumb situations, but often they can think their way out as well. Describe a reasonable working enslavement, and see if any thing they try seems like it might work. They are still low level enough that you aren't being too cruel by taking all their stuff (well except for a wizard's spellbook), but perhaps on the way out they can retrieve some of it, or steal something cool.

[Laserlight]

Just asking "are you sure" sometimes gets you a glassy eyed look and an uncomprehending "Yeah...". Any time I have to ask "Are you sure?", I also explain why their idea seems ill advised--it may be obvious to me but sometimes they had a completely different picture of the situation.

Barbarian: Torg jumps off the wall!
Me: The wall is 60ft tall, so IF you do that, you'll take 6d6 damage, that's 21 damage on average and about half your total HP, right? And then when you land, you'll be surrounded by three hill giants and two ogres, and you'll be prone so they'll have advantage on their attacks. So, do you really want to jump off the wall, or do something else?

And sometimes they say "Yep, I jump" as the barbarian did in that case.

So in this case I would explain to them why a LR is a bad idea and ask if they want to do it anyway. If they do, and they TPK, well, it's a learning experience.

[sophontteks]

If you say "Are you sure?" And they proceed only to find out the consequences, they'll learn fast the next time you ask. Course if you say "Are you sure?" and they proceed without any real consequence, they won't really heed the warning next time.

[BoxANT]

while taking a long rest, one of the dwarves (or PC w/ good perception) hears a noise in the dark...

being paranoid of an attack, someone yells "DRUEGAR!"

the party awakens, and (hopefully) starts running away

commence with exciting chase scene, and their (possible) escape

[RazorChain]

My players are currently in a Duergar stronghold. They entered through a secret tunnel to save some Dwarven allies and succeeded in freeing half of them, and killing 6 Duergar guards over 3 encounters (my party of four are all level 3).

The issue is that I gave my players a time limit of 6 hours before the prisoners were put on work rotation and the guards were changed, but after these 3 encounters they have retreated to a "safe-spot" for a long rest.

During their sleep, the Duergar will discover that the 4 prisoners have escaped and that 6 Duergar were killed, and will definitely take action. The Dwarves were exhausted, unarmed and ball-n-chained so I don't think the prison break conclusion is believable.

Their plan next session is to just head back in to save the other 4 Dwarves through a network of secret tunnels they found out about (which requires journeying back the way they came - where they killed previous guard patrols).



Personally, I think that these ruthless Duergar would follow the trail of corpses back to their resting spot and ambush them in their sleep. Is this fair of me to do? It would lead to them being killed or captured (the more likely option), and would also probably conclude with the Ranger's Animal Companion being slaughtered instead of being enslaved for mining etc.

Is there another way? What else could happen? How can I make a prison escape more interesting? Help?! I really didn't expect them to just go to sleep without hiding the bodies or covering their tracks! :smallsigh:


That's not what happens. The Duergar will find the corpses and exclaim "A corpse! Someone is skulking about." Then they will search the vicinity in an alert state for couple of minutes until they settle into their normal routine again. This gives your players the time they want to strike again and free the other prisoners.

[Finback]

Another option:
the party is approaching, when they stumble upon (hopefully, they're stealthing) two duergars who are patrolling this branch, arguing if it's drow invaders seeking to destabilise duergar power bases, or just dwarven terrorists. This gives the party the chance to a) rethink how they approach this ("Oh, we might encounter more guards") b) a chance to be creative ("Let's kill these two, and plant evidence that it's the drow. Maybe we can distract them to another area with a "drow invasion"!)

Or perhaps the duergar guards are too busy watching for the PCs, they don't realise that the remaining dwarves are going to seize their own chance and start their own escape, so the two groups can meet halfway unexpectedly - players in a battle, and suddenly, four more dwarves, angry, exhausted and Having A Bad Day They Are Going To Take Out On Anyone In Their War become their backup.

[GreyBlack]

My players are currently in a Duergar stronghold. They entered through a secret tunnel to save some Dwarven allies and succeeded in freeing half of them, and killing 6 Duergar guards over 3 encounters (my party of four are all level 3).

The issue is that I gave my players a time limit of 6 hours before the prisoners were put on work rotation and the guards were changed, but after these 3 encounters they have retreated to a "safe-spot" for a long rest.

During their sleep, the Duergar will discover that the 4 prisoners have escaped and that 6 Duergar were killed, and will definitely take action. The Dwarves were exhausted, unarmed and ball-n-chained so I don't think the prison break conclusion is believable.

Their plan next session is to just head back in to save the other 4 Dwarves through a network of secret tunnels they found out about (which requires journeying back the way they came - where they killed previous guard patrols).



Personally, I think that these ruthless Duergar would follow the trail of corpses back to their resting spot and ambush them in their sleep. Is this fair of me to do? It would lead to them being killed or captured (the more likely option), and would also probably conclude with the Ranger's Animal Companion being slaughtered instead of being enslaved for mining etc.

Is there another way? What else could happen? How can I make a prison escape more interesting? Help?! I really didn't expect them to just go to sleep without hiding the bodies or covering their tracks! :smallsigh:

Well, consider it a learning experience.

What I would do maybe is have the duergar split into search parties to look for the PC's. During the long rest, roll investigation checks (say, 3 of them) to check for whether they're found or not. After that, maybe the duergar wouldn't necessarily engage straight away but rather start preparing for the heroes. They call for reinforcements, maybe even call for the foreman. Then, AT the 8 hour mark (before they can put their armor on and get ready), I would ambush them with 10-15 duergar at once and maybe have the duergar offer them the chance to surrender. Throw the corpses of the dwarves they were supposed to rescue at them, and then make the rest of the adventure escaping from the mine.

[Magzimum]

Firstly, it is NOT that the players messed up. When players make poor decisions, EVERYONE (incl DM) messed up. Good or bad, D&D is always a team effort of players + DM.

But I have a suggestion to solve the problem: It appears that problems only occur after 6 hrs, so you as a DM have to interrupt that long rest after 1 hour. Give them a short rest, so the HP is increased, but then create an event which motivates the players to keep moving and leave the area.

Ideas:

Perhaps one of the dwarves would very clearly state that he recalls another group of adventurers entering, freeing some prisoners, and then falling asleep in the dungeon itself. They are now dead. Maybe the dwarves, despite their exhaustion want to keep going? Maybe the dwarves will interrupt the long rest?
Perhaps a spirit wanders these caverns, and gives good advice?
Perhaps some traitor Duergar wants to betray the other Duergar, and wants to help them escape, and wakes them to help them escape (you can let this guy come back later in your story if you like, great way to introduce an NPC).
Perhaps they just have a nightmare, and wake up after only 2 hrs, getting only a short rest.
Perhaps water starts leaking from their hiding spot, and slowly (but literally) flushes them out before their long rest is complete.

[sophontteks]

I dunno. I feel like if the DM and the players are always working together then how could there be a challenge?

There has to be risk and consequences. Something to overcome. If the DM works with the players through every bad decision, they may begin to feel invincible. Why would they make creative decisions or take the game seriously when some ex machina always saves them at the last minute?

If the players fail to overcome a challenge, maybe the DM didn't provide adequate solutions, or maybe the players actually did screw up. I think its the later here and if the DM coddles them too much the risk of death goes away and with it the reward for overcoming challenges feel less earned as well.

[Segev]

I dunno. I feel like if the DM and the players are always working together then how could there be a challenge?

There has to be risk and consequences. Something to overcome. If the DM works with the players through every bad decision, they may begin to feel invincible. Why would they make creative decisions or take the game seriously when some ex machina always saves them at the last minute?

If the players fail to overcome a challenge, maybe the DM didn't provide adequate solutions, or maybe the players actually did screw up. I think its the later here and if the DM coddles them too much the risk of death goes away and with it the reward for overcoming challenges feel less earned as well.

Partially agreed. Where I think the DM needs to work with the players is in making sure that the "bad decision" isn't due to the players not being the characters. That is, the characters can see that the river is a frothing rapid with rocks just waiting to cut them. The players know there's a river there, and the DM might've described it as "white water" and with "rocks jutting out," but after thirty minutes of play - perhaps with a fight against some frustrating archers who've ridden their flying mounts to the far side of the river - the players may forget those details and just remember "it's a river." "I can swim," thinks one player, "So while it's a risk, I can probably get across it to fight those things!"

If the DM looks agog at the player, and just lets him jump in, then tells him that his 25 on Swim wasn't enough, the player is going to be rightly upset that the DM didn't remind him that it's not a placid and clear river, but a raging rapid frothing with danger.

[sophontteks]

Oh yeah, I agree with that. And it's really bad to just allow a player to kill themselves when most likely they just don't understand the situation completely. You warn them every time.

But man, if you warn them that the river is frothing and comfirm if they really want to do that, and they do it anyway, the DM should not water down the consequences. Better to have a character die then make all consequences seem superficial.

[Segev]

Oh yeah, I agree with that. And it's really bad to just allow a player to kill themselves when most likely they just don't understand the situation completely. You warn them every time.

But man, if you warn them that the river is frothing and comfirm if they really want to do that, and they do it anyway, the DM should not water down the consequences. Better to have a character die then make all consequences seem superficial.

Right. It's about Agency, both ways. To have it, one must be properly informed of what one's character would know, so one isn't being robbed of Agency by lack of understanding of what is going on. One must ALSO be permitted to do things that have consequences, or one lacks Agency because one's choices are meaningless.

[Darkbru]

I’m a pretty firm believer in the decisions made need to have consequences. Not that I’m looking to kill my party, but if they decided to literally take a long rest in the middle of a duergar compound after killing 6 guards the best they could hope for is slavery and a slain pet. If, however, the pet were given a perception check to notice the incoming duergar and alert tha party I would rule that they do not gain the benefit of a long rest and have to fight to stay alive. Up to you, but they made their choice and there needs to be a logical result based on those choices.

[furby076]

I dropped a bunch of hints (subtle ways of saying "are you sure?", "you backtrack through the caves, passing the bodies of fallen foes", etc.). The weird thing is that they came up with ideas when they first dispatched the Duergar, but never followed through with them; such as making it look like a Grimlock attack. I just feel like they really messed up here. x.

Setting other things aside, your hint isn't good, and in general hints (even good ones) suck. In your mind it's obvious "OMG i almost flat told them the answer". What you think makes sense may not dawn on the players. I'd give a reminder "hey guys, remember, you have 6 hours before XYZ". Nothing wrong with a dm giving suggestions "also, you haven't covered your tracks...too late now considering where you are...so, want to take a nap?"

[Ronnocius]

Setting other things aside, your hint isn't good, and in general hints (even good ones) suck. In your mind it's obvious "OMG i almost flat told them the answer". What you think makes sense may not dawn on the players. I'd give a reminder "hey guys, remember, you have 6 hours before XYZ". Nothing wrong with a dm giving suggestions "also, you haven't covered your tracks...too late now considering where you are...so, want to take a nap?"

The OP says that his players explicitly talked about their time limit and decided to take a rest anyways.

[Ding]

Most of your players seem to have a decent amount of experience with D&D, so I wouldn't go too easy on them. They've played enough to suffer real consequences. That said, I think it's very possible the six-hour window simply slipped their minds while they were fighting the guards, rescuing the dwarves, etc. If it was my campaign, I'd give them one final chance to rethink their decision at the start of your next session.

Option 1 would be to have the rescued Dwarf NPCs (who would be pretty familiar with the schedules and routines of the Duergar by now) point out that taking a long rest without hiding the bodies AND just before a changing of the guard is a terrible idea, and will most likely get both the party and themselves killed. Maybe phrase it in the form of a question or tentative suggestion so that it doesn't feel to the players like you're forcing them to change their decision -- just let it serve as a reminder. If they do it anyways, I wouldn't feel that bad about a TPK, or mass imprisonment and loss of all valuables. I would still make some rolls regarding whether or not the Duergar find them, how many they send, how stealthy they are, etc, just to give them a chance. They might run. But if they die, they die.

Option 2 would be to simply summarize the events of last session, making sure to emphasize the six-hour limit they were operating under, and then retroactively confirming with the players that they still choose to take a long rest without hiding bodies, etc. If they change their minds, good. BUT, you have to make it clear to them that your generosity in this situation isn't something to expect in the future, should they do something this dumb again. There can and will be real consequences. Otherwise, they'll just keep making silly mistakes with dire consequences, then get upset if you don't bail them out. And if they don't change their minds, again, they kind of deserve what they get.

Obviously you can also ex machina something, or send only a small group of Duergar after them, but personally I think the Duergar would be smart enough to realize that whatever enemy slaughtered their normal guard patrol without suffering any casualties should probably be exterminated with overwhelming force and extreme prejudice. After all, your party didn't show the Duergar any mercy :smallwink:.

[Plantae]

You could remind your players of the situation at the start of your next session, but it sounds like you already gave them quite a few reminders.

I think it's much more natural for the rescued dwarves to warn them. In fact, it would be strange if they didn't point out the obvious danger in resting for such a long time in enemy territory.

If your players persist, it's probably fair to give them a short rest, as it sounds as though the Duergar wouldn't be able to track them down immediately. And then have their sleep be interrupted by a Duergar scouting party.

How difficult you make this encounter is really up to you, but I think there's a reasonable middle ground between a mere warning and a complete slaughter. I'd throw just enough enemies at them to make it a harrowing encounter in their current condition, the kind that could go very badly if the players have some bad luck or make poor tactical decisions. You might even have one or more of the prisoners they just rescued get killed, to hammer home the gravity of the situation.

If they lose, it makes sense to me that they'd be captured, as the Duergar are in the habit of taking slaves. If they win, they suddenly have a huge problem - they've blown the element of surprise, and the Duergar will be actively hunting them. They'll have to decide whether they still want to try and rescue the prisoners or if they'd rather cut their losses.

If they go with the former, they have an uphill slog ahead of them. If they go with the latter, the rescued dwarves aren't going to be very happy that their brethren were left behind. They're too weak to protest too much, but they might harbor a grudge against the PCs for the tactical error that doomed their compatriots to slavery.

[Samayu]

My players are currently in a Duergar stronghold. ...

So, Mojake, how did it turn out?

[Caesar]

I think it's much more natural for the rescued dwarves to warn them. In fact, it would be strange if they didn't point out the obvious danger in resting for such a long time in enemy territory.

So much this. The DM speaks thru his world and especially his NPCs. That is how he creates the narrative and maintains emmersion.

"We barricade the secret room and prepare for a long rest."

"The dwarves you have freed grow increasingly alarmed at your actions.. 'whhhat are you doing? We cannot rest here it isnt safe! theyll find the bodies and then they will find us and then we will all be slaves, or worse...please! We MUST leave this place before they find us!,"