I think it would be nice if we can get valiant alternative heroes as well.
These heroes will focus on a different kind of justice compared to the valiants, they would kill for the greater good of all.
They could start out as enemies (some misunderstanding or are known enemies of the valiants themselves) during the story mode and eventually join the heroes in their goal to save arathos.
They have the same buff/stat bonuses as the valiants.