Ben 10 Omniverse: Season 8, Episode 9

8 - 9: The End of an Era

In an alternate future timeline, Ben 10,000 and Kai Green (at this point in time, Kai Tennyson) are at Plumbers' Headquarters having a party for Grandpa Max because he is retiring from the Plumbers and Rook is being promoted to be in charge of the Plumbers until Maltruant, Exo-Skull and Subdora secretly attacks Plumbers' Headquarters to get the Annihilaarg and the Dwarf Star for Maltruant to become more strong. Ben 10,000 and Kai Tennyson both discover that their ally Chrono Spanner is actually their own ten-year-old son, Kenneth Tennyson.