Ben 10 the Justice Leaguer

Ben tennyson, saviour of the universe billions of times, stopped the universe from getting destroyed, and stabbed Vilgax with a sword carried by an old man who died.

Many more things have occurred for the 16 years old boy, but that's for another time.
The universe is now at peace....kind of, there are still bad guys wanting the usual 'take-over-the-world' things and such. Though, with all that's happened to him, being flung into another universe different from his for a second time, is something he won't be getting used to anytime soon.