A summary of the episode ("The Castle of the Overlord")? More information on Nya's development? LEGO Ninjago - Aired Order - All Seasons - TheTVDB.com
Based on the title "[S11E27] Corruption," this episode is part of (specifically from the Legacy of the Green Ninja/Season 2 arc often re-indexed, or associated with the Dark Island narrative). [S11E27] Corruption
Lloyd, Misako, and Sensei Wu rush ahead to stop the Garmatron from reaching the coast. Key Themes A summary of the episode ("The Castle of the Overlord")
The Ninja pursue Garmadon to the coast. Kai, Jay, Zane, and Cole are forced to stay behind to deal with the newly evil Nya. [S11E27] Corruption
The sudden, forced turn of a close ally (Nya) creates high emotional stakes for the team.