Building 10 rooms

FUNGAL SHRUB:      PLANT
HALF-LEVIATHAN: MONSTER
CANNIBAL SCORPION: VERMIN
BRASS GHOUL: HUMANOID
SINGING DEMON: BOSS
SLIME FOWL: CRITTER

E G
| | | |
H--A--B--I
| | | | | |
D--C--F
| |
J
Room A.
SIGHT: Empty, rusted iron cages hang from hooks in the wall.
Cube-shaped room w/ square sliding puzzle on plinth in centre. Fetching missing piece from room G and solving puzzle will completely reconfigure dungeon, reality around PCs. Roll a new dungeon, place PCs in random room.
Room B.
SIGHT: Room is part of ancient castle, walls are slabs of stone.
Time moves slower the closer you get to the middle of this room. TYROXIS the OBSEQUIOUS PRINCESS, wearing a crown, wielding GLASS SCIMITAR caught in stasis at exact centre. In fact crown is cursed - you can remove it pretty easily, breaking the curse and halting the effect, but in the time it takes you several years will have passed outside. TYROXIS the OBSEQUIOUS PRINCESS is notorious character from history.
Room C.
Dungeon oasis. Lake of pure water, grove of FUNGAL SHRUB, SLIME FOWLs and BRASS GHOULs drinking together in peace. If you start a fight here everyone in the dungeon will find out about it and regard you with unremitting hostility forever.
Room D.
SOUND: Hiss of steam escaping through cracks in floor.
SIGHT: Flowers bloom everywhere, even where they shouldn't. Especially where they shouldn't.
SINGING DEMON's walk-in wardrobe. One entrance through wardrobe doors, one hidden behind layers of clothing. Careful searching will reveal a IMMOVABLE BOOTS, two living scarves that try to strangle you and a BRASS GHOUL in fancy dress.
Room E.
SMELL: Dry and musty, like mummy wrappings and black mold.
Observatory. Star charts, half-ground lenses, celestial globes, tables of astronomical data (looks like random numbers) and pulsar emissions. SINGING DEMON 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 F.
Pool of stagnant water with treasure chest at bottom. Treasure chest contains bound, gagged ANGLEGG the GREEDY BISHOP, is temporarily watertight. If released ANGLEGG the GREEDY BISHOP will demand vengeance on BRASS GHOUL in room G, offer reward for assistance in this matter.
Room G.
Bedchamber of three, four BRASS GHOULs. Sodden and filthy. Careful inspection of damp rags that serve as bedding will reveal a(n) SKULL OF SPRING in surprisingly good condition, but forces save against filth fever.
Room H.
Space is bent in such a way that walking down this tunnel will bring you out in room E.
Room I.
Staircase wraps around inner wall of well. One exit high up, one at water level. Water pitch black. HALF-LEVIATHAN that lives in well usually not hungry, can be roused to surface by ringing bell at very top of shaft.
Room J.
Looks like empty room. Actually maw of cave leviathan, those weird stalagmites its teeth. Glimmer of treasure deep in gullet is pyrite lure. SLIME FOWLs pick dead flesh from between teeth.