I am seeking advice, suggestions, anecdotes, ideas, links or resources for running a Hexcrawl adventure in the underground/Underdark. I have been reading up on 3.0 & 3.5 Forgotten Realms material particularly Underdark, Lords of Madness and general geology. I've also been playing Dwarf Fortress II again. They are traveling to a lost Dwarven city that sits under 2500 ft of seawater. Like all parties, they can try a stealth or "break in the front door" approach by going in the ocean entrance, but it's heavily defended with chokepoints making success possible but far less likely than approaching laterally or from underneath by using a lost Dwarven map of the city and the surrounding region.
I am running a high level campaign (14th level) in a homebrew setting. The party is (6 PCs with 3 cohorts optionally in the background) seeking 2 Orbs of Dragonkind, the Red Orb and the Sea Orb. The party just obtained the Orb of Void Dragonkind (custom item - similar to other orbs except spell like ability is Vampiric Touch) in the last session. The Sea Orb is in now in the tentacles of an gargantuan Aboleth advanced to 26d8 (300 hp built using the monster creation rules) with some more magic abilities. The Aboleth with the Orb is holed up in the flooded ruins of the ancient Dwarven Capital, which is located on the Dwarven Sea floor and extends for more than a mile down. The area is guarded by Aboleths, Skum, constructs, water elementals and now Sea Dragons. Finally, located near the Aboleth Villain's lair is a gate to a massive Dwarven conducted greater demiplane called the Stone Ledger, which is holds all the lost knowledge of the Ancient Dwarves who colonized the continent and who, despite amazing arcano-technological discoveries, were obliterated by Aboleths when the flooded roughly 5-10% of the continent and sank the land in the region, creating their own tectonic plate by dragging land down 0.5 - 2.0 miles.
I started reading this and thought this could be fun.
I have also heard the 4e Underdark book is a great resource.
Bump.
You sound pretty set compared to many who are looking for suggestions.
Anything specific you're looking for insight on?
-TimD
You sound pretty set compared to many who are looking for suggestions.
Anything specific you're looking for insight on?-TimD
I suppose it does sound set. I guess I mentioned more context than necessary.
I have never run a hexcrawl, nor have I run an adventure in the Underdark, nor an underwater adventure. While I believe I can do a decent job, I am trying to draw on the experience of others considering I am trying three unknowns at once. Pitfalls to avoid, suggestions on making Hexcrawls more fun, suggestions on creative encounters in the Underdark or Underwater (don't have to be Aboleths), that sort of thing.
Thanks :-)
Even though it’s a high level campaign it sounds as though resource management should be a factor given the alien environment. Mostly this shouldn’t be too much but is an additional drain on resources and a badly timed or unfortunate encounter might mean that some vital life supporting spell or equipment expires or is lost.
As a keen diver, the first thing I would note is that being underwater requires some form of breathing technique. At high level that should be easy enough but in real life, using scuba equipment means divers have to surface slowly to avoid getting the bends. An over-simplification but if depth(metres) + time (minutes) > 50 (e.g. 30 mins and 20 metres) then they need to decompress before surfacing and the length of time required to decompress gets exponentially longer. A 30 minute dive to 60 metres takes over 30 minutes to decompress even using oxygen to accelerate the decompression. If the method of breathing has a limited duration characters could be faced with the choice of a serious bend or drowning.
Diving at night and/or out of visual reference has additional navigational challenges as even moderate currents are imperceptible. A light source is easy enough, but add that to large caverns and water currents and the party may not have any visual reference to realise they are moving in a different direction to the one they think they’re walking in. They may be heading north through the water, but moving in a SE direction over the ground (a compass wouldn’t move). Also those currents move in three dimensions and change direction with tides or around obstructions. Navigation and getting lost could be a real issue. Those characters who are negatively buoyant will still sink though. Many divers find depth control to be a challenge and will follow the bottom for visual reference not realising that they are much deeper than intended. Out of sight of any visual reference the first clue (other than depth gauge) is a change in mask pressure or ear pressure and in stress situations usually cleared subconsciously without realising what it means.
Sound travels more quickly underwater, so although sounds can be heard, their direction cannot be discerned by creatures who are attuned to the speed of sound in air. Also water transfers heat about 20 times more quickly than air. 20C/68F water will quickly chill somebody who is not adequately insulated.
Those currents mentioned earlier make interesting additions to encounters or scenarios. A current runs quickly through narrow spaces and can bounce characters around off of walls and also split the party if the current splits down two corridors. Surge currents, typically caused by waves, move back and forth quickly. Is dexterity impacted by an underwater current
Many spells are likely to function differently underwater – do fire spells or heat spells still work? Do electrical tacks create a ball instead of a line? How about Fly and levitation? Are verbal components possible underwater, can a somatic component be achieved whilst swimming?
Random idea based on Hugo's post.
You can probably repurpose the rules regarding wind speeds to cover currents, including making concentration checks to cast while in a current.
I had not considered currents, which the city would have. Repurposing the rules for wind as currents as a great idea. I am imagining a similar repurpose of gust of wind as gust of current, so to speak. I can see Aboleths using the artificial magic currents as a form of Controller style magic (such as into a solid fog - if that even works underwater). I am surprised at getting lost underwater - low visibility and sometimes no discernible landmarks.
As far as temperature, I think Frostburn from 3.5 had rules involving wet clothes making things another temperature category. That could be adapted for a similar effect unless they were aquatic sub type?
Hugo, what do you think would be good rules for the bends? I imagine fort save against either lethal or non-lethal (non lethal is already pretty lethal underwater for non-water breathers). Bends can affect sea creatures too right?
Great ideas so far!
Currents: main difference between wind and water is that you can feel wind, but you cannot feel a current unless it is turbulent and turbulence is caused by obstacles or colliding currents. Water will carry you at the speed of the current so a 10 foot/round current will move you 10 feet without you feeling it.
Bends: I've had a bit of think about how to represent this in game terms but it could be paperwork heavy. Bit of background, the bends is caused by nitrogen loading under pressure. Every 10 metres of depth is equivalent of 1 atmosphere of pressure so at 10 metres depth somebody breathing from scuba equipment is breathing twice as much air as they do at the surface. If they then suddenly surfaced the nitrogen in the air they breathed would expand to double the volume and create bubbles - this is the bends. To counter this affect divers ascend slowly and equalise their bodies internal pressure with the external water pressure.
To simulate this: Every round count the number of 5' squares deep they are and add this to their overall nitrogen loading (this can be scaled to minutes etc and using average depths to make it less cumbersome). If they have less than 400 units then they can safely surface if ascending slowly.
The depth should be adjusted so that at 5 feet they lose 2 points per round, 10 feet 1 point a round or 2 points if they are above 800 units and at 15 feet 2 pints a round if over 800 units. and at 20 or 25 points they do not gain or lose points. Once surfaced, they lose 1 point a minute
So this looks like
Depth Loading
0 -1/min
5 -2/rd
10 -1/rd, -2/rd >800
15 -2 rd >800
20 0
25 0
30 +6/rd
35 +7/rd
40 +8/rd
A fort check is required if
Depth=0 or 5 and Loading >400
Depth=10 and Loading >1600
Fort Check DC is Loading/20
A Bend check is also required if the ascent rate exceeds 5 feet/round. The DC for this depends on the speed of ascent and the pressure differential, so it is less likely to have an effect at depth
I would suggest that for the first 100 feet of depth that the following table is used
Rate Fort DC
5 - 0
10 - Loading/20
15 - 2* loading/20
20 - 3* Loading/20
For 100 to 200 feet halve the DC, and half again for the next 200 and so on
In terms of effect, there is a good Wikipedia article I would say that for every 5 (or 10)the DC is failed the effect goes in the order: temporary, Minor, Moderate, Major, Death.
The severity of the bend determines the onset and the type of bend determines the type of injury. A major spinal bend can easily result in paralysis, a minor brain bend might make concentration and/or perception more difficult. A minor skin bend results in some itching that might prove distracting. The Wikipedia should help you flesh out an effects table, but the main theme should be debilitating rather than damaging.
Hope that helps
Technically sea creatures do suffer from the bends and this has been recorded. However most human cases are caused by nitrogen, the oxygen also creates bubbles but these are absorbed by the body and would only be an issue if the body was pulled out so fast that it didn't have the opportunity to use the oxygen.
As sea creatures' gills only extract oxygen from the water they would not suffer the bends in the same way as humans do. So in gameplay terms they would not suffer the bends unless teleported from great depth to the surface.
If a human (or demi-human) had breathing apparatus that simulated gills, i.e. bypassed the lungs and put the requisite amount of oxygen into the bloodstream, then they would not suffer the bends.
Note a human can only breathe about 1.4 atmospheres of oxygen (140% at surface level, 70% at 10 metres, 47% at 20 metres etc) before being at risk of suffering oxygen toxicity and having a seizure. Below about 65 metres, normal air is toxic to humans and scuba divers who exceed this depth will breath hypoxic gas mixes. Normally this is Helium as it is less narcotic than oxygen or nitrogen.
The narcotic effect of oxygen and nitrogen is often described as the equivalent of a tequila slammer every 10 metres/30 feet. At depth players under the narcotic effect of pressurised air (again not using gills) may have to make a Fort save as if they had drunk the equivalent amount of alcohol. In real life the narcotic effect is often a contributing factor in scuba accidents and so it is probably suitable to roll every time there is an unfamiliar decision or skill required
Another thing to consider is thermoclines, the wall where two different temperatures of water meet. It shimmers and looks a bit like looking through a thin sheet of glass or ice.
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As sea creatures' gills only extract oxygen from the water they would not suffer the bends in the same way as humans do. So in gameplay terms they would not suffer the bends unless teleported from great depth to the surface.
If a human (or demi-human) had breathing apparatus that simulated gills, i.e. bypassed the lungs and put the requisite amount of oxygen into the bloodstream, then they would not suffer the bends.
Note a human can only breathe about 1.4 atmospheres of oxygen (140% at surface level, 70% at 10 metres, 47% at 20 metres etc) before being at risk of suffering oxygen toxicity and having a seizure. Below about 65 metres, normal air is toxic to humans and scuba divers who exceed this depth will breath hypoxic gas mixes. Normally this is Helium as it is less narcotic than oxygen or nitrogen.
Hmm. I think I would rule that the spell water breathing would protect from the bends. I also will make an assumption for continuity sake that spells like [i] teleport [\i] and [i] shadow walk [\i] cause the body to adapt pressure automatically. I like your rule ideas Hugo. I'll have to over simplify it to reduce the complexity even though it will be less realistic. I'm also going to make a 2nd level spell that can protect against decompression sickness for hours per level by keeping pressure normal for the creature's environment. I don't want to make it irrelevant with to many protections, but magic should make it easier to deal. Even with some added protections against it, those are resources that could be used for something else and can be dispelled, causing the body to safely adapt to current pressure. I would imagine an anti- magic field would cause instant compression which would be catastrophic (fast onset nitrogen narcosis, burst ear drums, eyes getting crushed or Death on failed fort saves, depending on depth), let alone the fact that your lungs are compressed underwater too.
Does breathing underwater with a tank get harder as pressure increases?
I'll post an attempt at simplified pressure rules today or tomorrow and let me know what you think. It's been fun learning about how this works and different animals avoid the bends. Sperm whales apparently keep oxygen in special air containing spaces and collapse their lungs to avoid Nitrogen absorption by stopping gas exchange.
I think it might help you if you think of the 3 different methods of getting oxygen and follow the effects from there:
1. Breathing is achieved by gills or similar and oxygen at the correct concentration is absorbed directly
2. Air is breathed at the surface and held underwater
3. Air is breathed into the lungs at pressure underwater
The bends will only affect the 3rd case.
In the 2nd case the gas will contract but counter-intuitively the length of time the person can stay underwater increases. This is because the oxygen concentration increases, when they ascend the pressure decreases and the concentration also decreases to a point where it cannot be absorbed by the body. Free divers often encounter this phenomenon and it is known as a shallow water blackout. The partially collapsed lungs aren't an issue as they expand back to normal size at the surface. In case 3 the lungs would explode if the breath was held during an ascent as the expanding gas cannot escape
Ear drums will burst if there is a large pressure difference, as they contain air at ambient pressure and will affect any of the three breathing scenarios, but eyes won't be crushed as they are liquid which doesn't expand or contract significantly.
Breathing from a tank does get harder the deeper you go but not really noticeably so. Modern regulators are finely tuned so that a small amount of negative pressure (caused by sucking) almost force-feeds you air but a small amount of positive pressure will seal it again.
I imagine that the sperm whale avoids nitrogen absorption because of the narcotic effect, rather than the bends as it is breath-holding down to a 1000 metres or more.
I'd also recommend looking into the old 1st edition Dungeoneer's Survival Guide which had a lot of interesting facts (and some now rather obsolete rules) for underground environments and hazards including characters going mad or getting depressed from not having seen the sun for far too long.
The old 2nd edition Night Below campaign (boxed set) is a good resource for Underdark based adventures too. It used to be available as a pdf online for a very reasonable price. Now it's proving to be somewhat harder to find so good luck with that.
Ooh. I did manage to find the DSG online as a pdf 'though.
https://www.youtube.com/watch?v=Jtyn1jJajjI
I found the DSG and Night Below pdfs. The DSG had rules that were mostly revised in Pathfinder, but you were right about the "underground insanity". I well remember that with my PC's followers if they bring the surfacer ones with him.
Night Below is reeeeaaallly good. There is a lot of good material, from natural hazards, to small sized settlements/tribes of underground humanoids, and ideas for unique treasure (there is a crown of derro domination ) that are easy to convert. Thank you for this suggestion - a good read for this subject. Reading the actual module is interesting because not only because of subject matter but also it's DMing advice. In the third chapter, there is a situation where if you are on good terms with the Rockseer Elves but insist on going down into the lowest level of the Underdark, the module tells you to increase random encounter sizes by 50% until the PC's return for advice. However, if you weren't allied, this situation does not occur.
@ Hugo - haven't been able to work further with those rules but still intend to
Bends: I've had a bit of think about how to represent this in game terms but it could be paperwork heavy. Bit of background, the bends is caused by nitrogen loading under pressure. Every 10 metres of depth is equivalent of 1 atmosphere of pressure so at 10 metres depth somebody breathing from scuba equipment is breathing twice as much air as they do at the surface. If they then suddenly surfaced the nitrogen in the air they breathed would expand to double the volume and create bubbles - this is the bends. To counter this affect divers ascend slowly and equalise their bodies internal pressure with the external water pressure.A Bend check is also required if the ascent rate exceeds 5 feet/round. The DC for this depends on the speed of ascent and the pressure differential, so it is less likely to have an effect at depth.
Do you think this simplification would work reasonably well, or is it too far off?
Bends - When a character that has breathed air into their lungs at pressure underwater, it can suffer from terrible pain from the Bends. A Bends check is required if a character is surfacing from water after breathing air non-magically from the deep. It is also required if the character ascends too fast after breathing air non-magically at depth.
For every 5 ft a character descends he gains 1 Load point. When a character does ascends 5 ft per round, a character can reduce their Load points by converting them to Unload points. A character loses 1 Unload point per round after ascending 5 ft - this means that if a character ascends at 5 ft per round, they will gain effectively lose 1 Load point per round and nullify Unload point gain. At the surface, a character loses 2 Unload points per round.
If a character accumulates a number of unload points that exceeds 1/2 character's hit dice + Con Mod, the character must make a Ascend Bends check every time she gains more unload points. If the character is between 0 and -200 ft, this check is made every round. If the character is between -200 ft and -2000 ft, this check is made once every minute. The Ascend Bends check is a Fortitude Save DC = Unload points + (-1 per 100 ft below 200 ft to a max of -20) + (-1 per 10 ft below 200 ft to a max of -20).
When the character reaches to the area from -20 ft to the water surface, the bends can also manifest. If the character's Load Points exceed 1/2 character's hit dice + Con Mod when they enter this subsurface/surface area, the character must a Surface Bends check every round until the character has reduced their Load Points below 1/2 character's hit dice + Con Mod. The Fortitude save for a Surface Bends check is DC is = Load Points. At the surface, a character loses 2 Load points per round.
It is possible to be required to make a Surface Bends check and an Ascend Bends check in the same round. If this occurs, the character must save against the higher DC +2.
If a character fails their save, they take 1d2 temporary Dex damage until they recover from the Bends. For every 10 the DC is failed the effect goes in the order: temporary, Minor, Moderate, Major, Fatal.
Temporary: 1d2 temporary Dexterity damage.
Minor: 1d4 temporary Dexterity damage, and is sickened. The sickened condition remains he receives remove disease.
Moderate: 1d4 temporary Dexterity Drain, and 1d4 temporary Wisdom drain.
Major: Paralysis, 2d4 Permanent Dexterity Drain, and 2d4 Permanent Wisdom Drain. If underwater, character will start to drown if paralyzed and/or reduced to 0 Dexterity.
Fatal: Death, whether by paralysis or in extreme cases, lungs bursting.