As promised, Kazu revealed the cover for Escape From Lucien on his Twitter just now!
In all it's amazing glory, folks.
Okay, as I suspected from examining the thumbnail, there's Vigo, Emily, and Trellis. The Colossus mech behind them is also holding Navin, Cogsley, and Alyson, which couldn't be seen in the thumbnail.
And again, I do believe I was correct in speculating that the elf in the backdrop is, in fact, a new character. Judging by the braids, I would suspect it's a female. (I was actually kinda hoping for a female elf character.)