MetaBen

MetaBen also known as GodBen is 30-year Ben wearng the Metatrix.
The Metatrix gives Ben the powers of every single alien in the Codon stream and their Ultimates with the abilities enhanced times fifty. Ben can use any alien's abilities, even all at once in any form, human or alien. He can also transform any part of his body into that of any other alien or Ultimate he desires. He has enough power to take out an army of Ultimate Way Bigs, seeing as has the strenght of more than 100 Ultimate Way Bigs not to mention his duplication and other enhanced powers.

Ben first gets the Metatrix In Ben 10: Meta Menace to fight MetAggregor after he takes the Omnitrix and absorbs all the power from it (all the aliens were unlocked) making him unstoppable enough to exact his revenge on the Levin/Tennyson family.

MetaBen also wears Forever Knight armour with the Metatrix symbol (a blue hourglass with the green infinity symbol behind it) on his chest and the sword Ascalon which was sealed into the Metatrix in a sheath on the left side of his waist.

MetaBen has also mastered his anodite powers as well as magic.

All these traits combined made him virtually the most powerful being in the Ben 10 universe, especially seeing as Diagon was still sealed within Ascalon. Although Ben eventually battles him again after his essence drives MetaBen insane.

After defeating Diagon, MetaBen regained his sanity and fixed the damage he had caused. Although, he needed to be nudged in the right direction by the presence of his teenage self as well as teenage Julie, Kevin and Gwen.

 BACKSTORY 

After Aggregor breaks out of jail, he finds Ben and kidnaps Julie (who is pregnant and married to Ben) and forces Ben to give up the Omnitrix for her. After doing so, Azmuth presents his latest and greatest invention to Ben, the Metatrix. Ben uses its powers to defeat Aggregor and continued to use it to keep peace until the essence of Diagon in Ascalon (which is in the Metatrix) overwhelms him and he slowly becomes a menace, up to the point where he becomes just as insane as Ultimate Kevin, until Paradox brings the young Ben, Gwen, Kevin and Julie to snap Ben back to his senses, after which he unleashes Diagon and battles and defeats him thereby vanquishing him. Azmuth then allows Ben keep the Metatrix.