500 years ago, Lumiere (the First Wizard King) and Licht (leader of the Elves) were close friends who wanted peace. However, a devil named Zagred manipulated humans to attack the elves during Licht's wedding.
You can find the episode with Arabic or English subtitles on several official and community platforms: 500 years ago, Lumiere (the First Wizard King)
Her true human form and her long-standing loyalty to Asta are finally explained. 500 years ago
Adapted from Chapters 205, 206, and 207 of the manga. 500 years ago, Lumiere (the First Wizard King)
To prevent Zagred from taking his body and grimoire, Licht used forbidden magic to turn himself into a massive, mindless Demon.