Ben 10 Ultimate Alien Season 1 Episode 15 — "Perplexahedron"

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The high-stakes race for the shards of the Map of Infinity reaches its most structurally complex and lethal bottleneck in the fifteenth episode of Ben 10: Ultimate Alien, titled "Perplexahedron." Having suffered sequential losses across the cosmos, Ben Tennyson and his allies follow Aggregor's trial to a mind-bending artificial planet custom-built to hide the final crucial key to universal reality distortion.

To secure the fourth fragment, the team must enter a massive, shifting multi-dimensional maze that defies the standard rules of navigation. Relying on Gwen's tactical intuition, Kevin's physical adaptability, and the evolutionary mutations of the Ultimatrix, Ben has to conquer a labyrinth that is actively trying to crush, slice, and burn any intruder who sets foot inside.

“This whole planet is a puzzle box. If we don't find the pattern, Aggregor wins and the universe is finished.”

Episode Summary

Ben, Gwen, and Kevin track the final piece of the Map of Infinity to the Perplexahedron, a giant, sentient cube-shaped artificial construct floating in the vacuum of deep space. Originally built by the enigmatic Professor Paradox, the structure consists of constantly rotating, interlocking rooms filled with incredibly lethal mechanical hazards. The team discovers that Aggregor has already boarded the station, treating its traps as mere inconveniences as his absorbed powers allow him to punch his way through the walls.

While navigating the deadly shifting chambers, Ben’s team encounters The Sentinel, a peaceful glowing entity tasked with protecting the core artifact. The Sentinel warns them that the maze shifts algorithms every few minutes, making forward progress nearly impossible without understanding its geometric properties. When Aggregor corners them inside a room equipped with crushing piston arrays, a vicious firefight breaks out, testing the absolute physical limits of the team.

Ben activates the Ultimatrix to tackle the threat, matching Aggregor's brute strength by debuting Ultimate Spidermonkey and later relying on Cannonbolt to survive the shifting momentum of the rooms. Although Ben successfully saves the Sentinel from being crushed by a closing bulkhead, the detour allows Aggregor to bypass the final security wall. In a devastating climax, Aggregor violently extracts the final piece of the map directly from the core terminal, completing the Map of Infinity and instantly teleporting away toward the fabled Forge of Creation, leaving the defeated heroes trapped inside a rapidly deactivating station.

Themes & Character Development

The Moral Dilemma of Choice: The narrative forces Ben into a brutal philosophical corner. When given the choice to secure the map piece or save the life of the innocent Sentinel, Ben chooses life, highlighting that his human core values remain completely untainted despite the risk of universal erasure.
Geometric Problem Solving: Shifting away from basic fistfights, the conflict highlights the importance of intellectual synergy. Gwen's spatial tracking and Kevin's engineering insights are vital to surviving the labyrinth's deadly traps.
The Horizon of Hope: Despite facing an absolute tactical defeat as Aggregor secures all four shards, the team's shared resilience sets up a final, gritty determination to chase the Osmosian warlord into the absolute origin point of space-time itself.

Production Details

First Aired: November 5, 2010
Created By: Man of Action Entertainment, developed by Dwayne McDuffie and Glen Murakami
Written By: Matt Wayne
Directed By: Butch Lukic
Produced By: Cartoon Network Studios
Art Style: Striking industrial cubist architecture, utilizing high-pacing kinetic camera pans, rotating multi-layered room filters, and glowing neon security boundaries to convey a sense of claustrophobia and continuous spatial motion.
Voice Cast:
- Yuri Lowenthal as Ben Tennyson
- Ashley Johnson as Gwen Tennyson
- Greg Cipes as Kevin Levin
- John DiMaggio as Ultimate Aggregor
- Dee Bradley Baker as Ultimate Spidermonkey / Cannonbolt / The Sentinel

Fun Facts & Trivia

Did You Know?

The architectural design of the Perplexahedron is a direct sci-fi homage to the famous real-world mathematical concept known as a Tesseract or a hypercube, which represents a fourth-dimensional geometric structure.
This episode serves as a thematic companion piece to the classic sci-fi psychological thriller movie *Cube (1997)*, sharing the premise of survivors trapped inside a shifting maze of lethal booby traps.
The artificial planet was structurally engineered centuries ago by Professor Paradox, intentionally designed with automated defenses to keep the final piece of the Map of Infinity hidden from malicious entities.
Ben's choice to save the Sentinel over prioritizing the map fragment was heavily debated within the fan community, serving as a massive character beat that defines his identity as a protector.
The explosive conclusion of this episode officially sets up the legendary season finale, *The Forge of Creation*, where a temporal anomaly brings young 10-year-old Ben into the future.

Legacy & Impact

"Perplexahedron" stands as a monumental structural climax for the first season's grand treasure hunt, praised heavily for its claustrophobic tension, fast-paced action sequences, and heavy psychological stakes. By taking away Ben's traditional environmental advantages, it forced the team to rely purely on their instincts, intellect, and internal bond.

The final, tragic acquisition of the fourth piece by Aggregor completed a multi-episode arc of failure that completely redefined the emotional weight of the franchise. It left fans completely breathless, setting the stage for an unprecedented cosmic intervention that would unite two distinct eras of Ben 10 history.