X = Ben + 2

X = Ben + 2 is the thirteenth episode and the season one finale of Ben 10: Alien Force.

Plot
A starship docks with an Incursion cruiser, dropping an Incursion named Brook off. He stops to talk to Commander Raff, one of the commanders. He explains that when they were exploring an enemy star system, they were ambushed by the bounty hunter Sevenseven and Princess Attea went missing. They report to Emperor Milleous, and he destroys Brook, sending Raff to the nearest inhabited planet: Earth.

Ben, Gwen and Kevin are arguing in Kevin's car for where to go. Incursions then appear and point their guns at the three, but Raff appears and stops them, as Kevin reveals he used to do business with Raff back when Kevin was a crook. Raff explains the situation to Kevin and Ben's team agrees to help after Milleous threatens to blow Earth to pieces with the Conquest Ray. Gwen uses the clothing to track Attea to a dam.

Sevenseven destroys the dam while trying to shoot Attea and it crushes Kevin's car, traps Gwen in a bubble and nearly drowns Sevenseven, Attea and Kevin in stone form. Ben decides to use the untested Celestialsapien transformation Alien X to stop the water and fix the dam. However, Sevenseven snatches Attea and Alien X is frozen in time. Ben soon realizes that in order for Alien X to do anything, he must convince one of the two personalities to agree with him, Bellicus, the voice of rage and aggression and Serena, the voice of love and compassion.

Raff teleports Gwen and Kevin, along with the Incursions and Kevin's car to Milleous. Milleous destroys planet Pluto to demonstrate the Conquest Ray's power. Even worse, Ben finds out that Bellicus and Serena do not want him to change back. Kevin absorbs his car's tires and takes the Royal Detonator, fleeing from battle. Ben makes Bellicus and Serena agree on saving the Earth, but it becomes difficult to convince them what to do. Gwen and Kevin get away from the Incursions chasing them and run into Attea and Sevenseven. Sevenseven releases Attea, but they then reveal Attea paid Sevenseven twice as much to overthrow Milleous.

Attea takes the Conquest Ray and imprisons Milleous, Gwen, Kevin and Alien X. When Ben sees this, he forces Bellicus and Serena to release him from Alien X's body. Before Attea can fire the Conquest Ray, Ben turns into Swampfire and defeats Sevenseven and the Incursions, and Milleous forces Attea to surrender.

Attea is thrown in stasis jail with her mother and Milleous lets Ben's team return to Earth without destroying the planet. Ben makes a vow never to go Alien X again, despite all the power a Celestialsapien possesses.

Major Events

 * Ben first transforms into Alien X.
 * Pluto was destroyed.

Debuts

 * Sevenseven
 * Incursions
 * Princess Attea
 * Emperor Milleous
 * Commander Raff
 * Bellicus
 * Serena

Omnitrix Alien Debuts

 * Alien X

Characters

 * Ben Tennyson
 * Gwen Tennyson
 * Kevin Levin
 * Bellicus
 * Serena

Villains

 * Sevenseven
 * Incursions
 * Princess Attea
 * Emperor Milleous
 * Commander Raff

Aliens Used

 * Alien X (first and only appearance in Alien Force)
 * Swampfire

Trivia

 * Tara Strong, the voice actress who voiced Ben in the original series, guest stars in this episode as the voice of Princess Attea.
 * We discover that Gwen not only has the ability to track where someone is, but she is also able to see what he/she is doing at the time.
 * Pluto is destroyed in this episode by Emperor Milleous to serve as a warning to what he'll do to Earth.