[s1e8] The Snake King -

The Ninja discover that Nya is the mysterious Samurai X.

Lloyd Garmadon is taken prisoner by the Serpentine after attempting to spy on them. Other Possible Matches [S1E8] The Snake King

If you are looking for a different series, "The Snake King" (or a very similar title) appears in these contexts: The Ninja discover that Nya is the mysterious Samurai X

Pythor challenges the other Serpentine Generals in the Slither Pit, winning their staffs and uniting the tribes under his command. [S1E8] The Snake King

The Ninja hold a tournament to see whose weapon will glow, believing it will reveal who is destined to be the Green Ninja.