When it is Kai's turn to watch over Lloyd, he drops Lloyd off at the Kiddie Arcade so he could continue to pursue the Samurai. However, upon hearing voices from a nearby back alley, Lloyd discovers a group of Serpentine preparing to head to the Lost City of Ouroboros. Lloyd rushes inside the Arcade and obtains a Rattla costume, disguising himself in order to sneak onto the bus and investigate the Serpentine's latest plot.
The other Serpentine Generals used the Serpentine Bus to break Skales out of prison. While evading the police, it ended up accidentally participating in the annual Ninjaball Run; although it covered a surprising amount of the course, it was taken out of the competition when it was involved in a pile-up along with the Darkley's school bus, the Postman's modified bicycle, Ed and Edna's jalopy, and the Ultra Sonic Raider. However, it was still functional enough for Skales to drive it to the finish line, where it picked up Lord Garmadon as he was cornered by the police and the Ninja.