Building 10 rooms

FLESH SLIME:     PLANT
SLIME ELEMENTAL: MONSTER
WITCH TOAD: VERMIN
SINGING GOBLIN: HUMANOID
BLIND MINOTAUR: BOSS
DESERT OWL: CRITTER

E
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G--C--J
| |
A
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I--B--D--F
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H
Room A.
SOUND: Muffled voices from next room.
Terraced volcanic pools of bubbling, sulphurated water, getting warmer as you get closer to the bottom. SLIME ELEMENTAL drinking from second-lowest pool, temporarily pacified by calming effects of hot spring, will not attack unless provoked.
Room B.
Big circular room, BLIND MINOTAUR armed with MORNINGSTAR OF THE BASILISK patrolling boundaries. BLIND MINOTAUR will not allow anyone to pass straight through crossroads. Doesn't mind you turning corners. Cheating by trying to turn two corners will be strictly punished.
Room C.
Couple of SINGING GOBLINs around shallow pit, gambling on combat between trained WITCH TOAD. Intruders will be hurled into pit, but if you wait long enough the furious loser will accuse the winner of cheating and a fight will ensure.
Room D.
SINGING GOBLINs in flimsy tin-pan armour, wielding long pointy sticks, riding poorly-tamed DESERT OWLs, practicing jousting.
Room E.
Bedchamber of three, four SINGING GOBLINs. Sodden and filthy. Careful inspection of damp rags that serve as bedding will reveal a(n) FLUTE OF THE ELEMENTS in surprisingly good condition, but forces save against filth fever.
Room F.
SIGHT: Walls carved w/ ancient glyphs, adorned w/ partial mosaics.
SINGING GOBLIN games room. Mildewed cardboard boxes, rotting tomes with amusing titles like Ye Olde Playeres Handbooke. Spotty SINGING GOBLINS 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 G.
SMELL: Air painfully dry.
Single incredibly-intelligent SINGING GOBLIN has found only space in dungeon where it is possible to just sit and think. If left to own devices will rule own kingdom on surface world in ~10 years.
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 DESERT OWL. If you do it will bless you. One SINGING GOBLIN elsewhere in dungeon is priest, knows secret to this.
Room I.
VIRYNGUS the OPPORTUNISTIC THIEF, playing the flute. Has no idea they're in a dungeon. Can see everything around them perfectly clearly, just refuses to believe it's a dungeon. Will confabulate other things it could be. Flute not magical unless you desperately need it to be.
Room J.
SIGHT: Floor covered w/ layer of gritty sand.
SONDLOSIA the WHISTLING PEASANT, with broken leg, desperately trying to fend off a couple of WITCH TOAD. Is carrying RAINBOW ELIXIR, which would be easier to take from their corpse.