Hmm, Cliffside Gorge city dominated by abberations?
GRELL.
You need Grell. First you have your floating Brain with beak and paralytic tentacles, that are competent sorcerers (of the higher castes), and create items of technomagic relying a on strange energies and forces of the natural world.
Now, add templates...
The Fused Aberration from Chaositech...
Any number of things from GR Advenced Bestiary (All templates, all the time)...
But make an aberrations aberation...
Pick another aberration you particularly like that has 4 or more leg like limbs...
Tauric (insert beastie) Grell - a multi limbed raking nightmare than can levitate into
dark holes in the ceiling to drop its paralytic tentacles on you while unleashing the power of it's lightning lances.
Grell PsuedoScience items are also not easily usable by non-grell, but they could find weird glyph carvings in some of the grell dominated sections that would allow the alienists to learn some of the basic grell science feats so they could make or use the lightning lances and similar thngs. I highly recommend Lords of Darkness from WotC for this.
Also in Lords of Darkness is the beholder epicurean who paralyzes and knocks enemies into a chasm filled with violet fungi to "season" his food.
And since the aberrations are underground, how about a fungal hobgoblin farm...essentially the Daelkyr has set aside a few old sparring or feasting rooms, and lesser beings defecate and drop all their refuse there, where they have mutated some of the originally enslaved bugbears into rooted fungal bugbears and hobgoblins...as large as their humanoid selves, they are now part giant fungus, rooted the floor, with limited limb movement, blind, but with blindsense, and fully functional mouths and vocal cords. They are intelligent, but completely helpless, and insane and because they are both fleshy meat, and fungal matter, with living brain tissue, and they constantly moan, and shriek and sob, they are both a soothing musical accompaniment to the area (for aberrations) and can provide for a wide variety of aberration dietary requirements.
Sounds like it'll be a fun adventure