I’d put money on it being Bill. The corpse looks a bit like him and a former wielder of Mjölnir has a decent chance of being the character to die in this particular story.
I’m not actually sure if Bill has died before, so that adds to it as well
I think that may be the likely choice. Going back several issues Thor destroyed Stormbringer. Thor said Asgard would need a champion not bound to Asgard or something to that effect. Bill promptly went out and took the Twi-Light sword from Surtur. Now that is a weapon that even a G.O.H. should fear. Does kind of look like Bill will pay the price. I still do not see where the " something is wrong with Asgards magic" fits in but it will become evident unless it has something to do with the next arc.