Building 10 rooms

DUSK CACTUS:     PLANT
ICE YETI: MONSTER
CIRCULAR MANTIS: VERMIN
BLACK IMP: HUMANOID
WERE-TROLL: BOSS
PRIMAL PANTHER: CRITTER

H C--E
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J--D--A--B F
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G I
Room A.
SMELL: Meaty reek of underworld flowers, like frying fat and potpourri.
SIGHT: Everything is coated in fine layer of snail slime.
Iron portcullis, BLACK IMP on other side asking substantial fee to raise it. Will slam it shut when you're directly under it to try and spike you to death. If you approach this from the other side the BLACK IMP will also be on the other side, it can squeeze through the bars.
Room B.
Mechanical platform that takes you from top of shaft to bottom of shaft w/ ease. Third exit halfway up shaft, goes by too quickly to jump to. Each time you use it, 25% chance that tinkering BLACK IMPs will jam the platform just below the third exit and attack from above.
Room C.
Pool of stagnant water with treasure chest at bottom. Treasure chest contains bound, gagged HOGGLET the SINGING SERGEANT, is temporarily watertight. If released HOGGLET the SINGING SERGEANT will demand vengeance on BLACK IMP in room C, offer reward for assistance in this matter.
Room D.
SIGHT: Walls are murky green glass. You almost feel like you can see through to the next room.
SMELL: Strangely cold, like being in a meat freezer.
BLACK IMP marketplace. Stalls selling rusted-through pots, moldy fruit, actual piles of shit. Violence prohibited in marketplace, they will not hurt you as long as you stay within the prescribed boundaries and don't break any of their weird taboos.
Room E.
Looks like three-way intersection. One exit actually trap, leads to immediate dead end and floor collapse. Then BLACK IMPs come in and start poking you w/ sticks.
Room F.
SIGHT: Bioluminescent bacteria gleam in the walls and the dark mud of the floor.
SMELL: Metallic tang of hour-old blood.
Bedchamber of three, four BLACK IMPs. Sodden and filthy. Careful inspection of damp rags that serve as bedding will reveal a(n) POISONED ROD in surprisingly good condition, but forces save against filth fever.
Room G.
SIGHT: Extremely high ceiling narrows to tiny skylight.
BLACK IMP games room. Mildewed cardboard boxes, rotting tomes with amusing titles like Ye Olde Playeres Handbooke. Spotty BLACK IMPS hunched over reasonably flat rock playing Humans and Hamlets with dice made of bone and precious stones. One of the dice is actually lucky.
Room H.
Shrine to dungeon god. Altar will curse you if you touch it unless you prepare the proper sacrifices, which consist of one ritually smothered PRIMAL PANTHER. If you do it will bless you. One BLACK IMP elsewhere in dungeon is priest, knows secret to this.
Room I.
Observatory. Star charts, half-ground lenses, celestial globes, tables of astronomical data (looks like random numbers) and pulsar emissions. WERE-TROLL mesmerized by whatever it sees through single enormous telescope. If you broke the telescope's lens you could climb out of the dungeon through it.
Room J.
SMELL: Rotten-egg brimstone.
WERE-TROLL bedchamber. Four-poster bed, priceless paintings kidnapped from world are hung on walls and artistically befouled. Fairy kept in cage as singing nightlight begs release, claims to be able to grant wishes, can't. Golden key to cage discarded in room A, WERE-TROLL concluded they will never need it. Cage highly portable, otherwise unbreakable.