Goblin Slayer S01E09 - There and Back Again

The party encounters a giant mirror in the sewers. The mirror, the mysterious creature they encountered, the horde of goblins, and the goblin champion that appeared - Goblin Slayer and the others try to get to the bottom of what's going on. They once again encounter the horde of goblins as well as the goblin champion, which gravely injured Goblin Slayer previously. But Goblin Slayer had a plan to take care of them once and for all.