The cover depicts the surviving mercenaries that Ceres mentioned in Chapter 12. Some fought the Scorpian Demon before it left them to go chasing after Ceres and the crown. There have been three demons so far: the bug, the bear, and now the scorpian. Just likes bugs and bears, there are real scorpians in this world, a bit like giant scorpions, but this one was a demon.
Viveka, Lares, Jocastia, Saqr, Stefan, Morpheu, Dolph, Wilda, Zafirah, Ethe, Linde, and Serpa... you've seen glimpses of about half of them throughout the story, but you certainly haven't heard their names. Try to guess who is who, and in which pages you might have seen them. Based on their names, what do you think their powers are?
Standing in front of them is some guy... oh wait, that's the spirit of Mephis that we saw taking over a guy on the ship in Ceres' dream! Mephis was the bad guy necromancer from an earlier chapter obsessed with soul-stealing.
I think the guy whose body he took over... is named... Bob? Something like that. I can't imagine it matters.