WIZARDRY

Based on the first Wizardry game "The Proving Grounds of the Mad Overlord", a group of characters enter a dungeon to confront the ultimate wizard to prevent him from reaching an unstoppable power. On their way they meet up with a few new friends who have their own battles to settle, but their paths lay together. (Source: Anime News Network) — Description from AniList community (anilist.co).