Snake Attack!

Snake Attack! is a Ninjago book released in 2012. The book takes place during Can of Worms and The Snake King.

Book's official description
Masters of Spinjitzu: a force to save the world!

''There's a new hero in town -- a mysterious masked Samurai who is stealing the ninja's spotlight! They complain of a competing hero, but Sensei Wu thinks competition will be good for them. Meanwhile, the ninja go on a snake mission which leads them to the snake arena. In the arena, the ninja are ordered to face another captured foe...the mysterious Samurai! Will this be the ninja's end? Or will a friendly face be behind the Samurai's mask?''

Blurb
Sensei Wu has trained his ninja warriors in the ancient art of Spinjitzu. Now he must help them reach their full potential. If he fails, Pythor and his evil Serpentine will destroy the land of Ninjago and all of its inhabitants. Kai, Cole, Jay, and Zane are used to being Ninjago's good guys. But there's a new hero in town––a mysterious masked Samurai who is stealing the ninja's spotlight! While on a quest, the ninja are captured and ordered to battle the Samurai. Will this be the ninja's end? Or will there be a friendly face behind the Samurai's mask?