My home Vaarn campaign (currently on hiatus) reached a point where the PCs were delving into the flooded artificial caverns beneath the city of Gnomon, ostensibly in the employ of the Water Baron but in reality seeking to disable his sabotage device. We will return to this narrative someday, and I don’t intend to spoil anything beyond the point my players reached. However, I thought it might be fun to examine a few of the creatures they encountered in their adventures in the depths below Gnomon, especially since these are all bespoke monsters that haven’t appeared in published material. 


Level 3, Armour 13, Morale +7, Appearing d8
Attacks: Claw (d8) + Claw (d8) / Hypersonic Scream (d6 + DEX save vs Deafened)

Abhuman troglodytes, blind and cunning. Their protruding ears and fanged maws give them a grotesque bat-like aspect. They are excellent climbers and can attack from any angle within the depths they inhabit. 

Deafened: PCs who have been deafened by a hypersonic scream gain the Wound ‘Deafened’. They cannot hear the speech of other PCs. When the party rests, Deafened PCs must EGO save to ignore the ringing in their ears and fall asleep. If they fail they do not benefit from a Long Rest.

Comments: these are the humanoid opponents found in the depths. The dungeon was designed for mid-level PCs, so the Shriekmen pack something of a punch, with two d8 melee attacks per round and a nasty debuff that can endure beyond the encounter. 


(Biological / Synthetic)
Level 4, Armour 18, Morale +5, Appearing 1
Attacks: Big Claw (d10 corrosive) + Small Claw (d6 corrosive) 

A crab-like amalgam of chitinous shell and rampant nanotech. The Rustacean feeds on metal corroded by its unusual biology. It is highly territorial and will attack non-metallic creatures as part of a dominance display. 

Corrosion: a successful hit from the Rustacean’s claws will corrode a metal item in the target’s inventory, rendering it useless. Armour corroded in this fashion loses -1 Defence per hit. Synthetic PCs damaged by corrosive claws also suffer d4 CON loss. 

If there is debate about which item should be corroded by a hit, flip a coin. On heads the players choose, on tails the Rustacean does. 

Comments: who doesn’t love the rust monster? I would heavily telegraph the item destroying potential of this creature, but smart players will realise they need to keep away from it. This is a monster that’s extra dangerous to synthetic PCs. 

Hydra Colony

Level 20, Armour 09, Morale Immobile; Cannot Flee, Appearing 1
Attacks: via d3 Hydra Tentacles + Fresh Growth (special)

A vast immobile colony of semi-intelligent hydrozoa. A mature Hydra is a mass of translucent blue jelly, roughly the size and weight of an adult elephant. The Hydra takes root in an aquatic environment and exudes hunting tentacles to ensnare prey, destined to be absorbed by the bulk of the colony. A Hydra Colony regenerates 10 hp per round unless burnt or doused in acid.

Fresh Growth: the colony spends 20 hp to produce a new Hydra Tentacle. This may be performed once per round.

Hydra Tentacle 

Level 7, Armour 17, Morale +10, Appearing d3 per colony
Attacks: Strangle (d10 ongoing, STR save to break free)

The hunting appendage of the Hydra colony. Lurid blue, translucent jelly-flesh. Hydra tentacles are fast-moving, strong, and fearless. The tentacles are blind but have acute hearing, and attempt to throttle their prey, and draw them down into the main body of the colony to be devoured. Hydra Tentacles regenerate 4 hp per round unless burnt or doused in acid. If severed they reanimate within an hour.

Hydra Polyp

Level 2, Armour 12, Morale +10, Appearing d8 per colony
Attacks: Engulf (d6 ongoing, STR save to break free)

Slow-moving offshoots of a Hydra colony. Lurid blue, translucent jelly-flesh. The Polyp seeks to absorb enough biomass to root and establish a fully-fledged colony. Polyps regenerate 2 hp per round unless burnt or doused in acid.

Comments: a nasty boss creature that defined the whole second area of the dungeon. The tentacles are ‘hunter’ monsters that constantly probed the middle levels of the depths, reacting to sounds and vibrations. The PCs never had to fight the Hydra colony directly, only its tentacles, and were eventually able to re-start a huge turbine which destroyed the body of the Hydra.

If they had chosen to fight the body of the Hydra, I would have used the stats above. The Hydra Colony will quickly overwhelm almost any group, due to its rapid regeneration, high health pool, and ability to create a new Level 7 monster each turn. This is a ‘puzzle boss’ rather than a combat encounter.

The polyps exist to be annoying, and are random encounters in the depths.

Lurid Lobster

Level 6, Armour 18, Morale 6, Appearing 1
Attacks: Claw (d8) + Claw (d8) / Lurid Spray (blast, CON save vs d6 rounds of Blindness)

An enormous, ill-tempered lobster with an abdomen filled with luminous toxins. The creature ambushes prey from underwater, spewing incandescent ink everywhere before attempting to grab a single group member and escape with the living prize. 

Blindness: Characters blinded by the Lobster’s spit make melee attacks with Disadvantage. They cannot use ranged weapons.

Comments: another random dungeon encounter for mid-level PCs. This is a solo ambusher with a debuffing area attack and high defence. Unlikely to be a party wipe but could be really nasty if you’re not prepared for it. In my home campaign the PCs tricked the Hydra into grabbing the Lurid Lobster before it could attack them. 

That’s all for today! The encounter table in the Gnomon Depths was rounded out with Glider Spiders and Behemoth Toads, which have both been detailed elsewhere. 


    1. Cheers Bill, I kept them to myself for a while as they were in active use but the players cleared the top two sections of the dungeon ages ago. I figured it was fine to let them see behind the curtain.


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