The Visitor

The Visitor is the thirty ninth episode of Ben 10 and the season 3 finale.

Plot
Two snowmobilers accidentally release an alien named Xylene from a strange container. Xylene locates the Omnitrix and attacks Ben, under the impression that he had stolen it. However, when Grandpa Max comes to defend, the two recognize each other as old friends. Xylene and Max reminisce later that night. Ben as Wildvine spies on them, catching Xylene asking Max to leave Earth and travel through the universe with her. Distraught, Ben runs back to the campsite, where he's unable to ward off an attack by one of Vilgax's remaining drones which has upgraded itself using parts from the Rust Bucket and has to rely on Max and Xylene for help. There, Xylene reveals that she was the commander of the ship bringing the Omnitrix to Earth when Vilgax attacked it, and that she had intended to send it to Max; Ben received the Omnitrix by accident. Ben runs off in shock and Gwen follows. The drone attacks again and captures Max.

Ben and Xylene reluctantly team up to save him. They track the drone to the docks where it has assembled technology from Max's Plumber suit, and a large quota of military grade tech. In the process of defeating the mecha, Xylene uses her knowledge of the Omnitrix to unlock a new form, Upchuck, which Ben uses to destroy the robot by literally chewing it up and spitting it back out. At that, Xylene prepares to leave the planet and repeats her offer to Max. Max declines, claiming that Ben and Gwen are his whole world.

Major events

 * The gang learned that the Omnitrix was meant to be sent to Grandpa Max and not Ben.
 * Ben first transforms into Upchuck.

Debuts

 * Xylene

Omnitrix alien debuts

 * Upchuck

Characters

 * Ben Tennyson
 * Gwen Tennyson
 * Max Tennyson
 * Xylene
 * Phil (flashback only)

Villains

 * Vilgax's drone

Aliens Used

 * Wildmutt
 * Heatblast
 * Wildvine
 * Four Arms
 * Diamondhead
 * Upchuck (first appearance)

Alien Forms Unlocked

 * Upchuck (unlocked by Xylene by the input of a specific code)

Spells Used

 * Armarus Umspecta
 * Emocha Objectia

Allusions

 * Xylene says to Max, "Max, we must stop meeting like this.", it's probably a reference to the video game Max Payne 2.

Trivia

 * This episode suggests that the Tennysons think Verdona is dead (this makes sense given Ben & Gwen's reaction when first meeting her), possibly due to her having returned to Anodyne.
 * Gwen uses an unknown spell to wash the dishes but ends up breaking them.
 * Gwen uses her balloon spell (Emocha Objectia) for the third time.
 * This is the first episode where they mention that the Omnitrix was originally intended for Max. It's mentioned again in Ben 10: Alien Force in the last episode, The Final Battle: Part 2 by Azmuth the creator of the Omnitrix.
 * The Tennysons' 38th stop is St. Louis.
 * Xylene reveals Upgrade's species which is Galvanic Mechamorph.
 * This the first season finale that does not have Ben rapidly shifting between his alien forms (although it does reveal a new alien).