The episode features a large-scale confrontation between Wizard Brace and the Ghost Trailers.
The anime ends without explaining several key mysteries, which are later clarified in the Light Novels: Mahou Sensou Episode 12
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) Mahou Sensou Episode 12