15. Perplexhahedron

Complete story — includes the ending

Following the events of the previous episode, Azmuth contacts Ben's team and teleports them to the location of the final piece of the Map of Infinity: a huge, cube-shaped structure known as the Perplexahedron, located in another galaxy. The team pursues Aggregor to the interior of the Perplexahedron, discovering that it is an enormous, shifting maze designed by Professor Paradox to protect the final piece of the map from all who are unworthy. Ben eventually deduces a way to navigate the maze, and the trio are able to outmaneuver Aggregor and beat him to the center of the Perplexahedron. There, they meet the Sentinel, an alien who exists to protect the map piece. Ben retrieves the piece, causing the Perplexahedron to begin collapsing; while they try to flee, Ben decides to go back to save the Sentinel. In the process, Ben and Aggregor battle, and Aggregor steals the last piece. The Sentinel, lamenting that all is lost, vanishes in Ben's arms; Ben, resolving to honor him, declares that they will stop Aggregor. Ultimatrix alien debuts: Ripjaws