Bio and who will be in this world

It's kinda like a remake

Fódlan the land of secrets and the land of light and dark. Over in the second age Men, Elves, and Dwarves allied in the last alliance to defeat the Dark Lord Sauron with his armies of Monsters. It was then Sauron was defeated but the one ring was lost and never found it. In the third age a girl named Byleth who had found the Ring must go but she needed help. It was then Y/n The Grey Wizard who helps the heroes from other worlds who where summoned by someone powerful. Will the the new fellowship survive this harsh war or will Sauron reclaim the ring and rule over Fódlan in darkness.