Hi These are some ideas that came to mind for your characters, but keep in mind I've only tried one of them
Ozymandias (bewitching brews): Dry desert air, dry and hot, passing over crumbling stone megaliths and plundered golden monuments, bearing a hint of the incense of lost Gods on its winds, or maybe
Omen, (bewitching brews): Deep, mysterious, and full of dark portents: oakmoss, juniper berry, myrrh and patchouli.
The Steamworks category is worth a look for this, but particularly:
Robotic scarab: Polished metallic notes, glossy leather, frankincense, star anise, and thin lubricating oils.
Smokestack: Creosote, coal, and industrial waste.
The only cold scent I've tried is Kumari Kandam: Thick incense, clay, stone, and hothouse blooms with a spike of frost, a hint of decay, and heavy, dolorous aquatic notes. This is cold for me, and I don't really notice the floral, so it could be worth a try. I think there are also some snowy scents in the salon category.
I noticed also that in the newbie mixer you mentioned a library type scent? I like Dee for that, which is leather, rosewood, parchment and incense; Aziraphale and Miskatonic University might be worth a try, too.
Hope this helps!