Big season arcs :

After the battle against the Negative 10, the Unlimited Force officially declare that Bellwood is saved. But an old foe, Aggregor, returns with a crazy plan : Wipe out the entire galaxy. Ben and his friends can defeat Aggregor once and for all ?

List of episodes :

11. Aggregor Returns :

Ben, Kevin, Julie, Ship and Rook discover that Aggregor have survived his previous defeat 3 years ago. Will they be able to stop him ?

12. Double Trouble :

Ben, Cooper and Kai investigate about a series of crimes committed by Rojo and Malware. The wielder of the Omnitrix unlocks a new alien : Slingshot.

13. Hypnomania :

Ben and Kai discover that Sublimino hypnotized several senior citizens across Pittsburgh.

14. Mutant Kevin :

Ben and Kevin found a device that can mutate the latter without being insane. Dr. Servantis wants to steal this artefact to restore Kevin's insanity.

15. The Sacrifice :

Albedo engages Aggregor in one final battle. Realizing that the latter will die, Ben and his friends try to stop the villain.

16. The Gauntlets of Creation, Part 1 :

Aggregor allies with Khyber to find a new object that can turn powerful the user.

17. The Gauntlets of Creation, Part 2 :

Realizing the threat that represents Aggregor with the Gauntlets of Creation, the Unlimited Force team up with the Negative 10 to form an alliance.

18. The Gauntlets of Creation, Part 3 :

Overpowered by the Gauntlets of Creation, Aggregor betrays Khyber and kills him before revealing his plan to destroy the Unlimited Force and the Negative 10.

19. The Gauntlets of Creation, Part 4 :

The Unlimited Force and the Negative 10 prepare their assault against Aggregor. More allies join them for the plan.

20. The Gauntlets of Creation, Part 5 :

The combined forces of the Plumbers, the Unlimited Force and the Negative 10 battle Aggregor in one last stand. Many casualties ensues.