Troll Leaders and Troll-Hags

Trolls are a horrible race of carnivorous humanoids that dwell in the wild and rugged places of Mystara. Although the common troll is well-known to many adventurers, there are other variations that are only rarely encountered. Note that the social structure and reproduction put forward here are my own ideas about trolls and may not fit with other folks ideas about how trolls breed or congregate. 

Common Troll

Art by David Sutherland III, from AD&D 
1st Edition Monster Manual

Name	Common Troll
Armour Class	4
Movement	120ft
Hit Dice	6+3*
THAC0	13
Attacks	2 claws/1 bite
Damage	1d6/1d6/1d10
Special Ability	Regeneration (3hp/rnd)
Save As	F6
Morale	10
Alignment	Chaotic
Treasure Type	D
Intelligence	Low (6)
Size & Type	Large Humanoid
XP	750

Common Trolls are the trolls so often encountered by adventurers. They attack with tooth and claw, and regenerate from most wounds, though not from acid or fire damage. All common trolls are male and are birthed by troll-hags (see above). 

Troll Leader

Name	Troll Leader
Armour Class	4
Movement	120ft
Hit Dice	10+5*
THAC0	9
Attacks	2 claws/1 bite
Damage	1d6+1/1d6+1/1d10+1
Special Ability	Regeneration (3hp/rnd)
Save As	F10
Morale	10
Alignment	Chaotic
Treasure Type	D x 2
Intelligence	Low-Average (9)
Size & Type	Large Humanoid
XP	1600

Troll Leaders are common trolls that have survived long enough to become bigger and tougher than most of their tribe, and as such have bullied their way into a position of leadership. This is typically over a tribe of common trolls that may include one or two troll-hags. 

Troll-Hag 

Art by Marta Duda-Żarczyńska, source

Name	Troll Hag
Armour Class	6
Movement	120ft
Hit Dice	4** to 10**
THAC0	17 or better
Attacks	2 claws/1 bite
Damage	1d4/1d4/2d8
Special Ability	Regeneration + spells
Save As	MU4-10
Morale	10
Alignment	Chaotic
Treasure Type	D
Intelligence	High (14)
Size & Type	Medium Humanoid
XP	175 (at 4HD) or more

Troll-Hags are female trolls and are prolific breeders, producing litters of troll pups, the vast majority of which are male common trolls though perhaps 1 in 20 will be troll-hag pup. They have between 4-10 hit dice and also can cast spells as a magic-user of level equal to their hit dice. Troll-hags are typically a lot smarter than most trolls, and are often the power behind the throne in troll tribes. Like other trolls they can regenerate at 3hp/round, even after they have been supposedly killed (regenerating even when below 0hp). However, they also share the vulnerability to fire and acid, which they cannot regenerate from. 

They are known to work with other hags such as annis, sea and night hags and if they cannot join with a troll tribe , troll-hags have been known to join with other hags to form a coven. Their spell use seems to be innate rather than learned and tend towards enchantment and illusion, and their selection can seem rather eclectic to human mages who might prefer direct damage spells. 

Troll Pups and Juveniles

Name	Troll Pup	Troll Juvenile
Armour Class	7	5
Movement	90ft	120ft
Hit Dice	2+1	4+2
THAC0	17	15
Attacks	2 claws/1 bite	2 claws/1 bite
Damage	1d2/1d2/1d4	1d4/1d4/1d6
Special Ability	Regeneration (1hp/rnd)	Regeneration (2hp/rnd)
Save As	F2	F4
Morale	6	8
Alignment	Chaotic	Chaotic
Treasure Type	nil but check for adults	nil but check for adults
Intelligence	3	6
Size & Type	Small Humanoid	Medium Humanoid
Experience Points	35	200

These immature trolls are rarely found without parents, either normal trolls or troll-hags. A troll pup can regenerate as long as it is not below -10hp. If reduced below that it is permanently dead. Troll juveniles regenerate in the same way as adult trolls, recovering from any amount of damage as long as it was not by fire or acid. 

Cave Troll 

image from The Hobbit: An
Unexpected Journey (2012)

Name	Cave Troll
Armour Class	2
Movement	120ft
Hit Dice	10+10*
THAC0	10
Attacks	1 club
Damage	2d12 +2
Special Ability	Regeneration (3 hp/rnd)
Save As	F10
Morale	12
Alignment	Chaotic
Treasure Type	D
Intelligence	Low (6)
Size & Type	Huge Humanoid
XP	1600

Cave trolls look like a cross between hill giants and common trolls. They commonly use clubs or crude axes or spears as their teeth and claws are not as pronounced as those of common trolls. They are petrified (i.e. turned to stone) if exposed to sunlight (like the trolls in the Hobbit which are based on Norwegian mythology). They are a lot rarer because of this, but they are larger and stronger than common trolls. Because of their vulnerability to sunlight they are mostly subterranean, only emerging at night onto the surface if hungry or otherwise urgently needing something. Nobody knows where they come from - some say they are only rarely born by troll-hags, perhaps one in a hundred pups produced. Others say they are not part of any natural cycle but are manifestations of malevolent and hungry spirits of the earth. 

Art by Dan Frazier, source

Trollkin 

Name	Trollkin
Armour Class	7 or better
Movement	120ft
Hit Dice	2*
THAC0	18
Attacks	1 weapon
Damage	1d8+1
Special Ability	Regeneration (1 hp/rnd)
Save As	F2
Morale	8
Alignment	Chaotic
Treasure Type	D
Intelligence	Average (10)
Size & Type	Medium Humanoid
XP	25

Trollkin are an apparent crossbreed of humans and trolls, and appear as ugly humanoids, about 7ft tall.  Some sages have suggested they are the product of polymorphed troll-hags seducing unwitting human males, though others sages say it is not through normal biology but through some form of dark sorcery. Troll-hags are happy to have trollkin as their servants and minions, though common trolls despise trollkin and will only tolerate their presence in the tribe if a troll-hag insists. Some trollkin have formed their own bands, sometimes under the command of a troll-hag. 

Although not as tall or strong as trolls, trollkin are typically smarter, almost as smart as humans, and can use many human items and weapons, typically swords. Their trollish strength gives them +1 to damage with any weapon used. If unarmoured their tough skin gives them an AC 7, but they can wear armour and will use the better AC. They can still regenerate slowly (1hp/rnd) as long as they are not reduced to -10hp or below (at which point they are killed outright). As with other trolls they cannot regenerate from fire or acid damage. 

 

The Village of Whiteheart

The village of Whiteheart is almost the southernmost settlement in the Northern Reaches, where the Soderfjord Jarldoms meet the hilly realm of Gnollheim. It is only a village, with 750 inhabitants, but it is still the centre of the Ozurfold Jarldom, a small fief of only 1500 folk, half of whom are in Whiteheart itself. The other half are scattered across small hamlets and farmsteads nearby. 

The village is in a vulnerable position, dangerously close to both the Great Marsh and also the hills of Gnollheim. This has been addressed in two ways. Firstly Whiteheart has a sturdy pallisade and wooden gatehouse. Secondly the Jarl, Magnusson Half-Hand, is encouraging other Jarls in Soderfjord to help out with a wall between his Jarldom and the wilderness, the Sodervirk. The grand plan is for the wall to act rather like Hadrian’s Wall in the north of England, with guard towers every half mile, but a lack of funds, labour and political will has left the project in limbo. Nonetheless, Magnusson Half-Hand is persisting with the Sodervirk, sending materials, labourers and guards to the wall as the opportunity arises. Whiteheart does not have a proper standing force, but can muster a militia of about 120 1st level fighters (armed with spears, shortbows, leather armour and sometimes wooden shields) in emergencies. 

Trade involves livestock, some vegetable farming, timber and some fishing. Although there are ores and minerals in the hills to the south, the area is too dangerous to mine. The Otofjord river is the primary trade route and is considered the safest. The fact that it leads almost directly to Soderfjord City itself is very convenient, and means that as long as the villagers have river craft, they have a reliable connection to civilization. There is a road of sorts eastwards to Wilmik in Olvasfjord but this is more of a trail, with parts that are unsuitable for carts and wagons. And of course this trail runs just north of Gnollheim, so the threat of gnoll raiders deters many merchants from using this trail. 

There are two major congregations in Whiteheart, one dedicated to Odin, the other to Heimdall, both with their own clerics who view each other with some rivalry but understand they both have common foes. The village midwife is also a cleric of Frigga. 

Adventurers arriving in Whiteheart will find there is no actual inn, and villagers will be rather suspicious of them. Are they spies? Are they fugitives? Durstig Brightsword might take it upon himself to question any PCs. Initially the PCs may be told they can sleep within the palisade but not in any building until they have proven themselves - there are plenty of problems and tasks that adventurers could deal with. Once the PCs have started to show they can be trusted then certain villagers may open their doors to them. Durstig Brightsword may let them stay at his place, partly out of gratitude for helping to defend his village but also so he can continue to keep an eye on them. 

source

Map of Whiteheart

1. The Feasting Hall. Can seat up to 200 people for a feast. If Jarl Magnusson approves, visitors can stay in the Feasting Hall. The upper levels are Jarl Magnusson and Brynhild's personal abode but the ground floor is frequented by many villagers. 
2. The Stone Tower is the last refuge in the event of the palisade being overrun. It is 40ft/4 storeys tall and contains the armoury and various emergency provisions. 
3. The House of Heimdall. This is both a shrine of Heimdall and also the home of Durstig Brightsword. 
4. The gatehouses
   a. River Gate: The path north follows the river towards Soderfjord city. 
   b. Ford Gate
   c. Forest Gate: This leads to the less travelled path east towards Wilmik
5. The Smithy. This is the workplace and residence of Brugnor Bladebringer and his apprentices.
6. The Sheep Pens. This is a collection of enclosures for keeping livestock safe, if either raiders are nearby or in preparation for selling or transporting dowriver. 
7. The Tannery: This smelly place is home to Garthar Gnollbane
8. The Sacred Grove of Odin. Here Thragnir Oathkeeper conducts sacrifices and ceremonies to his patron immortal. 
9. Skald's Rest. This is home to Thorfei Silversong. 
10. The Healing House: This is home to Hraffni Wifefriend and can act as a makeshift hospital, with sick and injured villagers resting here. 
11. The Ford. This part of the Otofjord river is only 2ft deep, and can be crossed on foot or by cart. 

NPCs of Whiteheart

Jarl Magnusson Half-Hand: 9th level Fighter, human male, align Lawful, Str 16, Int 12, Wis 12, Dex 10, Con 16, Cha 14
Magnusson Half-Hand is leader of the Ozurfold Clan and Jarl of the Whitereach Valley. He feels he is in a difficult position, caught between the raids, feuds and skirmishes that so often happen between the Jarls of Soderfjord and the predations of the chaotic humanoids of the wilderness to the south, especially the gnolls of Gnollheim. He has a defensive attitude and strategy in his rulership and is perhaps the one keen advocate among the Jarls for the construction of the defensive wall, the Sodervirk. Although naturally wary of complete strangers, once someone has earned his trust, he will treat them as friends and allies, and for this reason he has a careful approach to adventurers. If the adventurers help keep Whiteheart safe then he will offer them food, shelter and whatever Whiteheart can provide. If they prove to be troublesome, Magnusson has no qualms about kicking them out into the wilderness. 

Brugnor Bladebringer: 5th level Fighter, human male, align Neutral, Str 16, Int 10, Wis 13, Dex 14, Con 10, Cha 12
As the village blacksmith for Whiteheart, Brugnor holds considerable sway. He tends to stay out of large-scale politics, but is always loyal to the village and what is best for Whiteheart. He is also keenly aware of the flow of both raw materials (iron ore, charcoal and the like) and finished goods (weapons, armour, tools, iron pots and pans etc) so his opinions are often around the economic wellbeing of Whiteheart. He has three apprentices who often carry out the less skilful tasks around the smithy. 

Hraffni Wifefriend, 4th level cleric, human female, align Lawful, Str 8, Int 14, Wis 14, Dex 10, Con 13, Cha 14
Hraffni is both the midwife for the village and also the local cleric of Frigga, goddess of marriage, childbirth and the home. She is Magnusson’s sister-in-law but rarely uses this connection - she prefers to stand on her own merits. She has proven to be a peacemaker, calming down quarrels that might escalate into bloodshed and Magnusson will sometimes ask her counsel in non-military matters, particularly in disputes and delicate negotiations. 

Thragnir Oathkeeper, 5th level cleric, human male, align Neutral, Str 14, Int 12, Wis 15, Dex 10, Con 15, Cha 12
Thragnir is the cleric of Odin, and the advisor to the Jarl in matters of war and rulership. He is faithful to his immortal, but he is also somewhat jealous and insecure, viewing clerics of other immortals as rivals who want a share of his power and authority. For this reason he can be quite cold towards Hraffni and Durstig. He has a pet raven called Gegni who he dotes on. 

Brynhild, 2nd level fighter, human female, align Lawful, Str 12, Int 12, Wis 10, Dex 15, Con 9, Cha 17
Brynhild is wife of the Jarl and sister to Hraffni. She is probably the most beautiful woman in the village (and some would boast in all of Soderfjord). She enjoys the finer things in life and sometimes wishes she was living in somewhere more civilized like Norrvik or Zeaburg. She is fascinated by tales from strange lands like Thyatis, Glantri and Darokin. 

Durstig Brightsword, 5th level cleric, human male, align Lawful, Str 13, Int 12, Wis 16, Dex 10, Con 17, Cha 12
Durstig is the local cleric of Heimdall, god of guardians and those who keep watch. Durstig also helps organise the village militia and ensures that the gates to the village pallisade are manned as often as possible. As befits his patron, Durstig tries to remain on guard against threats to the village, both in the form of humanoid raiders and also troublesome humans infiltrating. If strangers enter the village (such as adventurers) Durstig will keep an eye on them and report any wrongdoing to the Jarl who appreciates his vigilance. 

Thorfei Silversong, 2nd level magic user, human female, align Neutral, Str 10, Int 16, Wis 13, Dex 13, Con 12, Cha 16
Thorfei is unusual - a female Skald, a poet and singer of ballads and epics as well as teller of tales, a job usually reserved for men. She has dabbled briefly in magic and can still cast the most basic spells if needed, but her real talent and her role within the village is as historian and entertainer. Some say she can brew potions but she refuses to confirm this. Nonetheless she knows how to create infusions and poultices that may not work like potions of healing but still seem to speed up the recovery from wounds and prevent infection. She may not be a powerful mage but she knows magicians who dwell in larger places like Soderfjord City and she may introduce PCs to them if the PCs ask nicely. 

Garthar Gnollbane, 5th level fighter, human male, align Neutral, Str 14, Int 13, Wis 10, Dex 13, Con 15, Cha 7
Garthar is the village leatherworker for some of the time but he lost his wife and son to gnoll raiders five years ago and since then he has dedicated most of his time to hunting down and killing gnolls. He is perpetually angry and surly, difficult to get on with and prone to storming off on his own. Nonetheless he has unrivalled knowledge of gnolls, their habits and tactics and their whereabouts. The other villagers are disturbed at his latest practice of making leather out of gnoll skin. 

Geomorphs for the Temple of Chaos Divided and beyond.

Introduction to Geomorphs

I first encountered the idea of geomorphs in the AD&D 1st Edition Dungeoneer's Survival Guide with its appendix at the back. There were other products that reinforced this idea, including an old TSR pack of geomorphs and then the AD&D 2nd Edition Dungeon Builder's Guidebook. Although one could create geomorphs from any shape (and the DSG showed triangular and hexagonal geomorphs) I have always found square ones to be simplest to do and best suited to mostly-orthogonal dungeons. 

Art by Jeff Easley

The idea of geomorph tiles is that you can arrange them in almost any combination to create many different overall maps, rather like lego bricks. I tend to go for geomorph sizes that have an odd number of 10ft squares along any one side so there should be a 10ft square in the middle of each edge. This makes a common connection point between two geomorphs. Although one could have 2 connections or more per side, this decreases the likelihood of any two geomorphs linking up smoothly. A good geomorph system should allow for tiles to be rotated or flipped for a wider range of permutations. 

The size of a geomorph should be considered. The larger geomorphs can be impressive and complex, effectively dungeons in their own right. But it then becomes harder to create each one. Conversely smaller ones are easier to create but may lack character, seeming more like dungeon tiles than significant sections of dungeons. 

page 119 of the Dungeoneer's
Survival Guide, cartography by
Dave Sutherland

My prefered size is 190ft x 190ft square with a single connection at the centre of each side. This is what I have used for my megadungeon The Temple of Chaos Divided. In fact I would go so far as to say that megadungeons are the best use of geomorphs, followed by the Underdark/Shadowdark. An underground area where a single map, regardless of how large, may not be enough to detail all the encounter areas, is the best place for geomorphs. 

So should the DM assign monsters and other contents to a geomorph? Once the DM has decided what dungeon they are using the geomorphs for, yes of course, But a set of geomorphs is clearly  not bound to any one dungeon, even a megadungeon, therefore whatever the DM places in rooms in a geomorph for one dungeon, the same geomorph can be reused with completely different contents and inhabitants, not just in other dungeons but even within the same dungeon. Although a DM can create custom geomorphs for specific scenarios, this does somewhat defeat the idea of geomorphs being re-arrangeable and resuable. Actually, a custom geomorph created for one particular set of encounters the DM has in mind usually can be reused with quite different encounters, though it is possible the PCs will recognise the distinctive layout. 

Geomorphs can contain ways of going up or down, such as stairs, chutes, ladders or even just holes to drop down. However, I personally rarely use these as it is something else that needs to line up on the geomorph it is connecting to. This is why with the Temple of Chaos Divided has its central hubs which include the main stairs going up and down. The geomorphs attach to the edges of the hubs and so do not require ways of getting to the next level (though they can if the DM wants, and two of the examples below do have stairs). 

Some sample geomorphs

Despite my initial intentions, I have not added contents to these geomorph tiles as I believe this would distract from their purpose. If you want, you can fill them with monsters and treasure by careful design or by random rolls. I've tried to keep these relatively generic, suitable for a range of different dungeons, although they are all clearly created by intelligent creatures and not suitable for huge or larger creatures given their 10ft wide corridors. 

Logos Location #12: Berresford’s Ruined Tower

Based on original cartography by Dyson Logos; source

Introduction and Background

Thanks to Dyson Logos' generosity, he has made a large number of his high quality maps available for use. I have decided (with his approval) to incorporate these into locations within Mystara. This is a B/X D&D adventure for a party of  characters of levels 2-4 set in Norwold. It is a place that the PCs may look for after finding clues in the Ruined Arvorian Outpost, particularly if they rescue Berresford.   

This tower was built on a rocky outcrop on the west bank of a small river (too small to show on the campaign map) by early Alphatian settlers as a military outpost called Ironspire Tower, keeping an eye on creatures threatening the settlements on the shores of the Great Bay of Norwold. About 40 years ago (961 AC) the Alphatians were exploring around the area when they stumbled on a lair of Arvorians (perhaps Iseldek’s Drop?) and a battle ensued. The Alphatians retreated back to this tower, but the Arvorians followed them. All the Alphatians were slain and the Arvorians adopted it as their own, placing a squad of their junior members there and also recruiting local humanoids to bolster their forces.   

About a month ago a human trapper called Berresford rediscovered this tower that had been forgotten about. Thanks to great luck and skill he sneaked into the ground floor and found an amulet with a glowing gemstone inside, and then fled before the inhabitants could catch him. On his way back to Barathmir  he encountered a hunting party of the Alvini pack of lupins and mentioned the tower and the gemstone. He also encountered a wandering trader called Maevig Trostober, and he sold the amulet with the gemstone to her, with the promise he would find more from where that came from. Unfortunately this time the inhabitants of the tower were more alert: Berresford was captured and taken to the Ruined Arvorian Outpost for further interrogation where he is currently held until the PCs rescue him. 

Based on original cartography by Dyson Logos; source

As usual commonly used monster stat blocks are given at the end of the dungeon room descriptions. 

Ground Floor

1) 4 shield orcs + 3 crossbow orcs stand guard here, under orders to attack any non-orc, non-arvorian creatures that try to enter. The crossbows are already loaded so the crossbow orcs will shoot first then close in for melee. 

2) 5 shield orcs + 1 orc veteran warrior guard the stairwell. 

Orc Veteran Warrior: AC 5, Mv 90ft, HD 2 (10hp), THAC0 18, Att 1 battleaxe for 1d8+1, Save F2, Ml 8, Align C, 20 XP, equipment: Chain mail, Battleaxe, 25gp, 33sp

Upper Floor

3) This room has the stairwell going down as well as a round table with 7 stools. There are 4 crossbow orcs here, all with light crossbows, 10 quarrels and shortswords. The crossbows are already loaded so the orcs will try to shoot them before closing for melee with shortswords. 

4) This room has an orc subchief here with 2 shield orcs as henchmen. He is the leader of all the orcs in this building though he still answers to the Arvorians. This room also has a table with two large benches, as well as barrels of foodstuffs here. On the north wall is a ladder leading up to the top floor. Under the subchief’s bed there is a leather sack containing the orcs treasure: 1200sp, 400gp and 4 aquamarine gems worth 100gp each. 

Orc Subchief: AC 5, Mv 90ft, HD 3 (15hp) THAC0 16, Att 1 Sword +1 for 1d8+2, Save F3, Ml 10, Align C, 35 XP, equipment: Sword +1, Chain mail, dagger   

Top Floor

5) This is the observation post of the tower, with battlements around the walls and a flimsy wooden roof overhead that only keeps some of the rain and snow off. There are 6 crossbow orcs with light crossbows, 10 quarrels and hand axes. The crossbows are already loaded so the orcs will try to shoot them before closing for melee with hand axes.

6) This area has battlements along the wall and is open to the sky. There are no monsters here although a giant hawk has been known to roam the area, picking prey off when clearly above the trees. 

Based on original cartography by Dyson Logos; source

Upper Dungeon

7) Here are 7 skeletons, all with hand weapons. They have been instructed to kill any humans, elves or lupins. This means they will initially ignore any dwarves, halflings and gnomes though if attacked they will retaliate. 

8) 4 skeletons stand guard here with an Arvorian Junior Priest (Eldritch Crusader 3rd level) who commands them and the skeletons in room 7. She will command the skeletons to attack any intruders - she has encountered Berresford and other humans and decided she doesn’t like them. She is second in command here, answering only to the Arvorian leader in #14

Junior Priest: AC 3, Mv 60ft, HD C3 (12 hp), THAC0 18, Att 1 mace for 1d6+1 or by spell, Save C3, Ml 9, Align C, 50 XP, equipment: Banded armour, shield, mace, unholy symbol, amulet of undead command, 30gp, 15pp, Spells: Cure Light Wounds, Darkness

9) Stairs down to the lower dungeon. This is guarded by 2 zombie wolves, commanded by the Arvorian in room 8. 
Zombie Wolf: AC 6, Mv 90ft, HD 3+2 (hp 17, 14), THAC0 16, Att 1 bite for 1d6+1, Save F2, Ml 12, Align C, 50 XP, Spec Quality: undead - immune to poison, disease & mind-affecting spells, turned by clerics as ghouls. 

10) The Armoury. This has no creatures but boxes and barrels of supplies including shields, crossbows, hand axes and leather armour for orcs, and maces and scale mail for the Arvorians. 

Lower Dungeon

11) 4 Arvorian Acolytes (Eldritch Crusader 1st level) who will attack any strangers

12) Empty apart from beds for Arvorians

13) 3 Arvorian Acolytes (Eldritch Crusader 1st level) + 2 giant shrew the Arvorians have trained as a pet. The arvorians know about the secret door to #15 but are unlikely to use it. 
Giant Shrew: AC 4, Mv 180ft, HD 1, hp 3, 7, THAC0 19, Att 2 bites for 1d6/1d6, Save F1, Ml 10, Align N, 10 XP. Giant shrews get +1 to initiative rolls. 

14) Arvorian Leaders Quarters. An Arvorian Eldritch Crusader (4th level) dwells here and he commands all the Arvorians and orcs in the ruined tower. As well as his bed and a chest of clothes there is a table with a drawer. Inside are 400gp, 320pp, a peridot gem worth 400gp and a trio of small (coin-sized) softly glowing green crystals  that are actually eldritch crystals (no fixed monetary value but desired by the Arvorians). There is also a crude map that shows the location of this and several other Arvorian bases in the northern Great Bay area, including the ruined Arvorian Outpost and Iseldek's Drop. 

Arvorian Leader: AC 3, Mv 60ft, HD C4, 14 hp, THAC0 17, Att 1 Mace +1 for 1d6+1 or by spell, Save C4, Ml 10, Align C, 125 XP, equipment: banded armour, shield, Mace +1, unholy symbol, Spells: Hold Person, Cure Light Wounds, Darkness

15) Secret Compartment sits between two secret doors, one leading to #13, the other to #16. 

16) Empty apart from some fungi and mushrooms though the toads (16a) may occasionally climb out of the water here. 

16a) 2 giant toads lurk in this pool. If they fail a morale check they will try to swim along the submerged passage (#17) to escape. 

Giant Toad: AC 7, Mv 90ft/Swim 90ft, HD 2+2, hp 7, 10, THAC0 17, Att 1 tongue (see below) or 1 bite for 1d4+1, Save F1, Ml 6, Align N, 25 XP

Spec ability: tongue: 15ft range, no damage but drags small-sized target to toad for automatic bite Swallow small targets whole on natural 20, causing 1d6 damage per round

The submerged section: Areas 17, 18 & 19 are entirely submerged with no air to breathe. Navigating this without drowning will probably take magical aid. The Arvorians have left this section alone as two of their members have drowned trying to explore these places. It is quite understandable if PCs also completely leave this part of the dungeon alone, particularly if they realise the very real risk of drowning while fighting underwater and in the dark. The length completely underwater from 16a (the toad pool) to 20 (the watery cave with the crayfish) is about 170ft and in complete darkness.  And there is no telling if anyone trying to swim this length will take a wrong turn and end up face to face with an aquatic ghoul while running out of oxygen….

17) The submerged passage. The water goes all the way up to the ceiling. 

18) Lair of the Lacedon. A single aquatic ghoul dwells here. It feeds mostly on creatures in the river. The Arvorians are aware a ghoul is sometimes seen in the river at night but do not realise it has made its lair here. 

Ghoul: AC 6, Mv 90ft/Swim 90ft, HD 2*, 10 hp, THAC0 18, Att 2 claws/1 bite for 1d3/1d3/1d3 + paralysis, Save F2, Ml 12, Align C, 25 XP. Paralysis: each hit requires the target to save vs paralysis or be paralysed for 2d4 turns

19) More submerged passage. No fixed encounters here though the lacedon (#18) and giant toads (#16a) occasionally pass through here.

20) The watery cave: 1 giant crayfish (borrowed from AD&D) lurks here, feeding on any creatures that wander into the cave from the river. In the water there is a sunken rowing boat that still holds the skeletons of 2 humans who tried to escape when the Arvorians attacked. They tried to make off with 3500sp & 430gp but didn't get far. The loose coins are now scattered over the waterlogged boat wreck. The southern end connects to #19 the submerged passage.  
Giant Crayfish: AC 4, Mv 60ft/Swim 180ft, HD 4+4, 20hp, THAC0 15, Att 2 claws for 2d6/2d6, Save F2, Ml 10, Align N, 125 XP

21) 5 stirges roost here among the bones of various creatures. Scattered among the bones are some incidental treasure: 250sp, 33gp and a non-magical ring of silver and clear quartz worth 100gp

Stirge: AC 7, Mv 30ft/Fly 150ft, HD 1*, hp 5, 4, 3, 6, 2, THAC0 17 first attack, 19 thereafter, Att 1 proboscis for 1d3+ drain (automatic 1d3 damage per round thereafter), Save F1, Ml 9, Align N, 13 XP

22) Cave Mouth: This opens up on the river bank underneath the surface tower as noted on the ground floor map. 

Commonly used monster stat blocks

Arvorian Acolyte: AC 5, Mv 90ft HD C1, 4 hp each, THAC0 19, Att 1 mace for 1d6, Save C1, Ml 8, Align C, 10 XP, equipment: Scale mail, shield, mace, 20sp 

Shield Orc: AC 6, HD 1, Mv 90ft, HD 1, hp 5 each, THAC0 19, Att 1 hand axe for 1d6, Save F1, Ml 7, Align C, 10 XP, equipment: leather armour, shield, hand axe, 10sp 

Crossbow Orc: AC 7, Mv 90ft, HD 1, hp 4 each, THAC0 19, Att 1 crossbow bolt (range 80/160/240) for 1d6 or hand axe (melee) for 1d6, Save F1, Ml 7, Align C, 10 XP, equipment: leather armour, light crossbow, 10 bolts, hand axe, 10sp

Skeleton: AC 7, Mv 60ft, HD 1, hp 5 each, THAC0 19, Att 1 weapon for 1d6, Save F1, Ml 12, Align C, 10 XP, undead (immune to sleep, charm & mind affecting spells, immune to poison & disease)

Beyond this adventure

Although intended as a side-quest in case PCs follow up on Berresford’s account of where he found the eldritch crystal, this could be part of a longer chain of scenarios. The most obvious pointer for further adventures is the map found in the table of the Arvorian Leader in room #14. This map is loosely based on this one but not nearly as detailed. As well as the locations mentioned, the map could also indicate where to find more Arvorian bases created by the DM, or, if the adventurers are more interested in money, where treasure troves may be found.