how do you write a biography for a custom duel hero?

Yes, you can! In the game folder, go to DuelPresets and select, for example, Angel.h5p. Unzip the archive using an archiver, then open the file (using Notepad) preset.xdb and find the line and write there, for example, . Then, create a file bio.txt in the folder with the preset.xdb file, write the biography in Unicode format, save the file, and then put it in the archive. Now the hero will have a biography!

Added after 38 seconds
I apologize, here is that line.

Added after 45 seconds
()

Added after 45 seconds
BiographyFileRef href=""/