Rath of Con is the eighty-fourth episode of Ben 10.
Back stateside, Ben can't get into a cat cosplay competition, Top Tail, without a costume of his own; but when he goes Rath, a new cat-like alien with an attitude, Ben's newfound wild side quickly becomes much more than he bargained for.
The Tennyson's visit a cosplay con, based on cats. Ben laughs at Max and Gwen wearing cat outfits. The three walk through the building, and Ben notices a lot of cat themed objects. They make it to the obstacle course that Gwen will compete in. Gwen enters the competition being laughed at by the other contestants. Max and Ben both finds seats to watch the course. Each contestant failed easily, with the exception of Gwen. Max cheers on for Gwen, teasing Ben about not having a cat costume. Ben states that he doesn't need a costume when he has aliens, to which Max responds saying "Aliens aren't cats". Gwen prepares to continue on the course with the announcers counting her down. Ben cycles through his watch and finds a new alien, and Max finds a mouse in his popcorn. The mouse jumps out causing the whole audience to run away. Ben transforms into his new alien, revealing automatically naming himself Rath. Rath yells at Max telling him that he's going to compete in the obstacle course.
Rath sees a mouse and chases after it. In the mean time, Gwen breezes through the course with little to no struggle. Rath chases after the mouse, and ends up destroying most of the obstacle course in the prosses. Rath ends up falling in the water because of the mouse. Rath starts beating up the water for no reason.
Max congratulates Gwen on her success with the obstacle course. Gwen asks what was all the noise, and she notices Ben, as a new alien. Ben then times out. Max and Gwen helps Ben out of the water, telling him that he got a little carried away. Ben tells them that the alien was so angry, and he didn't feel like himself. Ben thinks of multiple aliens to use, but none of them can help with the situation. Ben transforms into Rath again. Rath tries to save people from the giant scratching post, and he begins cutting it down, but Gwen reminds him to use his inner cat. Rath gets all of the people off of the scratching post, and jumps down. After Ben times out, the judges arrive giving Gwen a medal. Ben asks for a prize since he saved all of the people. Steve gifts Ben his hat, from which a mouse hops on to Ben's head. Ben runs away while Max chases the mouse, causing Gwen to join in.