Building 10 rooms

HISSING MOSS:     PLANT
WOODEN MANTICORE: MONSTER
RUST SNAIL: VERMIN
HISSING ELF: HUMANOID
SKY SIREN: BOSS
FOREST PANTHER: CRITTER

H I
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B--C--D--E
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A F G
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J
Room A.
SMELL: Salty as sea-air.
SOUND: Almost-subsonic warble of cave songbirds.
ISHRAX the MOROSE SAILOR and SILKOXIS the PEDANTIC GLADIATOR fighting for possession of a INK OF THE WOLF, each with an extremely good argument for why it is rightfully theirs. Actually they stole it from the hoard of a SKY SIREN, who had it as a birthday present from their underworld pen pal and to whom it is of great sentimental value.
Room B.
ARBWOMP the CONSIDERATE WITCH, suffering catastrophic memory failure, no longer sure which way they came in. Single glowing blue mushroom in centre of room does nothing if touched. Memories leeched by prolonged exposure to its light. Eating it gives you all the memories it's absorbed.
Room C.
SMELL: Air disgustingly humid.
When you look down this hallway it seems to get narrower and narrower until you reach the end, which is child-sized. When you walk down it it stays the same size but you shrink. Works very differently if there's another way around.
Room D.
SOUND: Muffled voices from next room.
At least twenty doors. Most just lead into cupboards full of toxic mould, foul garderobes or empty sarcophagi. A few are unopenable, having nothing but rock behind them. SCABOXIS the KIND RAGPICKER has got themselves trapped behind one and there's a half-rotted BOOTS OF THE PHOENIX in the wardrobe behind another.
Room E.
SIGHT: Fetishes of bone and feathers dangle from the ceiling.
Beautiful woman made of glass, living in pit of liquid glass. Can see future with 95% accuracy. No particular reason to help PCs, but would rather like to get her hands on fragile glass chalice in room J (she'll eat it). Would be worth a lot if somehow extracted from dungeon and sold as artwork. Scream is like damp fingertip on rim of wineglass, summons WOODEN MANTICORE from another part of dungeon.
Room F.
Terraced volcanic pools of bubbling, sulphurated water, getting warmer as you get closer to the bottom. WOODEN MANTICORE drinking from second-lowest pool, temporarily pacified by calming effects of hot spring, will not attack unless provoked.
Room G.
Space is bent in such a way that walking down this tunnel will bring you out in room F.
Room H.
Enormous crystal-clear underground lake w/ HISSING MOSS growing around it, couple of FOREST PANTHERs peacefully drinking at edges. GLAIVE OF THE SWAMP lies clearly visible at very bottom of lake, which is much deeper than it looks.
Room I.
Map room. Globes, nautical charts, atlases, blueprints, guidebooks. SKY SIREN studying X-marked plan of faraway island, so enthralled that it has difficulty noticing PCs. Exquisite rug on room's floor seems like abstract pattern, careful study reveals it to be map of dungeon itself.
Room J.
Cornered, enraged, only semi-wounded WOODEN MANTICORE preparing to unleash its ultimate attack on bunch of spear-wielding HISSING ELFs who think they're doing much better than they are. If you wait you can get it before its ultimate attack recharges.