20. Four by Four

During their visit to the Twin City, Ben and Gwen sign up for some Laser Town awesomeness, but when Ben is teamed up with Kevin, the two must overcome their differences if they are to end up on top, especially since Gwen has been paired with the mysterious Fang. To make things worse, a hit from a laser causes Kevin to be trapped in the form of his version of Four Arms named "Quad Smack", and he needs to find a way to fix his Antitrix in order to change back.