Episode 12 — Mahou Sensou

After a massive magical explosion, Takeshi wakes up back at Subaru Academy, but he realizes he has been sent back in time to the First Great Magic War. The Ending Explained (Spoilers)

The anime ends without explaining several key mysteries, which are later clarified in the Light Novels: Mahou Sensou Episode 12

The finale of Mahou Sensou (Magical Warfare), Episode 12, is widely known for being one of the most confusing and abrupt cliffhangers in anime history. After a massive magical explosion, Takeshi wakes up

The episode features a large-scale confrontation between Wizard Brace and the Ghost Trailers. Takeshi and Gekkou engage in a final showdown

Takeshi and Gekkou engage in a final showdown. During the fight, it is revealed that their mother actually asked Bishop to kill Gekkou years ago—a revelation that shatters both brothers' previous understanding of the accident.