HP: Heir of Morgana Le Fay

A man from the 21th century gets reincarnated as Orion Le Fay, the son of the legendary dark witch Morgana Le Fay. In Order to survive the persecution of Merlin, Morgana sacrificed herself and froze him in unbreakable ice for a thousand years. When he woke up again he was in the timeline of the Harry Potter stories.