Ep 11. Many Happy Returns

In the eleventh episode of the first season of Ben 10: Omniverse, titled "Many Happy Returns", Ben's childhood rival, Kevin 11, returns to town and starts causing trouble. Kevin has been off the radar for a while, and his sudden appearance seems to have something to do with a stolen Omnitrix.

Meanwhile, Ben and Rook go to Gwen's birthday party, where they are greeted by old and new allies alike. However, Kevin's reappearance causes tension and suspicion among the group, and Ben must figure out how to deal with his old foe without ruining Gwen's celebration.

As the episode unfolds, it becomes clear that Kevin has teamed up with a dangerous intergalactic villain named Vulkanus, who has his sights set on the Omnitrix. Ben and Rook must put aside their squabbles with Kevin to team up and stop Vulkanus from getting his hands on the powerful device.

Throughout "Many Happy Returns", viewers see flashbacks of Ben and Kevin's past, giving insight into their complicated relationship. The episode also introduces new characters and amplifies the action and danger that fans of Ben 10 have come to expect.

Overall, "Many Happy Returns" is a thrilling and fast-paced episode that will keep viewers on the edge of their seats. Fans of the franchise will enjoy seeing their favorite characters return while also experiencing the excitement of new plot twists and adversaries.