This is my suggestion:
I am not sure about Iamos/Dewin, nor for Jonna being the particular one (though I think she should be there). Maybe we could switch her with 'some villain', though I don't think we'll be seeing anymore of Brocktree in order to place him in the cover. I'm also not certain about Stirling. I don't know how big part he'll play in the story. Finally, for the cover to be done correctly we need two Thingguys. That means that we either replace one figure with two or that the figures tagged as Jonna and some villain should become Thingguys and Jonna should replace Thingguy or something.