Ben 10: Hero Of The Universe
In the first episode Vulkanus returns with a techadon army. In the next episode Dr.Animo steals Astrodactyls DNA while Heatbat is on a rampage. Ben mentions Vilgax and that he will return someday.
Ben's omnitrix is still functional but soon he will have a new omnitrix in the last episode of Ben 10: Hero Of The Universe called the Ultraomnitrix.