Alright, I've got to jump in on this one because I finished 'Hero of Valor' last week and the antagonist thing is weirdly tricky. The cover and the first few chapters scream 'Lord Malgrim,' the dark sorcerer with the skull staff, right? He's the immediate threat pushing the hero's quest. But the deeper you get, the more you realize the actual main antagonistic force is the hero's own people, the Arcadian Council. They're the ones who betrayed his family, covered up the truth about his lineage, and are actively sabotaging him to maintain their power. Malgrim feels more like a consequence of their corruption than the primary source.
That said, the last act kinda pulls a swerve and implies Malgrim might actually be a cursed former hero himself, a weapon of the Council's earlier sins. So in terms of narrative weight, I'd argue the Council, led by Chancellor Vayne, is the true core antagonist. Malgrim is the scary monster in the forest, but Vayne is the one who put him there and sold the map to the hero's village.