Nice designs Angela! Sounds like a great challenge too. I'll check it out and might give it a go, though I'm late to the party already.
I'd say the hair golem and glass golem seem like the strongest ideas to me. Pretty clever. From what I can read they seem to value the concept art, so having an innovative theme seems like the way to go. Sorceress thumbs 1&2 have somewhat of a frosty feel to them (though changing the colour might change that just as easy). 3&4 seem fitting. There's this desert/hot/fire/glass-blowing/glassgolem kind of connection. I like your thumbs with the sandstorm angle a great deal as well. You could probably show sandy parts transitioning into glass and such. Would make for a nice contrast as well. Like natural glass.
Looking forward to further WIPS!