Thread:Dark649/@comment-38403463-20190323102514

https://guide.fire-emblem-heroes.com/en-US/duma_god_of_strength/

This is 100% official, canon, and in character (one of the main characters is the lne drawing the pictures). This guide states that Duma indeed is also known for creating the continent of Valentia alongside Mila (some other goddess) in the FEH continuity. And he joined the order of heroes, meaning that he can fight enemies that can hurt him and the order of heroes (main guys).

I think this might be a pretty reasonable upgrade imo, since its not a trailer or something that is from an outside source. Its a literal guide written by a main character in canon. 