Fused

Fused is the eighth episode of Ben 10: Ultimate Alien.

Plot
After Kevin and Gwen drop Ben off at his house, Ben can't get rid of the feeling that something is following him.

While sleeping, lightning goes through the electrical lines of Ben's house and then suddenly, Ra'ad, the last of Aggregor's prisoners, shows up and attacks him. He changes into Jetray to fight him. The battle ends when Ra'ad falls into a pool while charged up and shorts out. Ben, Gwen and Kevin take Ra'ad to Los Soledad where they put him in a containment cell.

Ra'ad tells Ben that it's his fault that Aggregor recaptured his friends (the other four prisoners). Ra'ad confirms that Aggregor is an Osmosian like Kevin and tells the trio that with the combined powers of himself, Bivalvan, Galapagus, P'andor and Andreas, Aggregor would be the strongest and most powerful being in the galaxy.

Ben offers to have Ra'ad work together with them to stop Aggregor. Ra'ad seems to agree with the deal, but the moment that Ben releases him, he attacks the trio, having read Kevin's mind that if things got worse, he would hand Ra'ad over to Aggregor. At that moment, the Ultimatrix detects that Ra'ad's DNA is uncatalogued. Ra'ad states that Aggregor used the Ultimatrix as a homing device to track the aliens.

To prevent Aggregor from finding him, Ra'ad tries to destroy the Ultimatrix with a lightning blast, but it launches its scanning wave at the same time. The mixing energies cause an explosion which blasts Ben into the wall and damages the Ultimatrix while Ra'ad has mysteriously disappeared. As Ben laments that things can't get worse, Aggregor shows up to recapture Ra'ad.

The gang try to fight Aggregor, but he proves to be too strong for them. The Ultimatrix finally lets Ben transform, but unfortunately, all that he can transform into is an Amperi. With no choice, Ben turns into AmpFibian and fights Aggregor. Unfortunately, he's still too powerful and decides to use AmpFibian as Ra'ad's replacement. Gwen then casts an unnamed teleportation spell to transport herself, Ben and Kevin away from Aggregor to Kevin's warehouse. Aggregor tries to track the Ultimatrix on his ship.

As Gwen recovers from her teleportation spell, Kevin has revealed he rebuilt the machine they had used to try to hack the Omnitrix in Vengeance of Vilgax to reboot the Ultimatrix and change AmpFibian back to normal, although Gwen and AmpFibian protest the idea. Suddenly, AmpFibian begins hearing Ra'ad's voice inside his head and begins acting like him.

It turns out that the blast accidentally trapped Ra'ad inside the Ultimatrix. He refuses to allow the Ultimatrix to be reactivated because Aggregor would find them. At the same time, he's slowly taking over AmpFibian. While Gwen holds AmpFibian / Ra'ad inside a mana sphere, Kevin absorbs a rubber tire to enable him to get near AmpFibian / Ra'ad and use jumper cables attached to the machine to reboot the Ultimatrix.

This time, the experiment is a success. AmpFibian and Ra'ad are separated, Kevin remains unmutated and AmpFibian has reverted to human. Unfortunately, with the Ultimatrix's signal restored, Aggregor is free to find Ra'ad. Rejecting Ben's offer to fight together, Ra'ad quickly escapes as Aggregor crashes through the roof. After dispatching Kevin and Gwen, Aggregor demands Ra'ad from Ben, who tries to fight him using Brainstorm, but Aggregor's weapon easily defeats him since it's designed to counter electrical manipulative speices.

Aggregor then tries to forcibly change Brainstorm back into Ampfibian by using his weapon on the Ultimatrix faceplate which nearly kills Brainstorm in the process. Outside, Kevin (who was thrown there by Aggregor) sees Ra'ad and yells at him about letting the only person who wanted to help him die. Ra'ad attacks Aggregor and saves Brainstorm. Ra'ad tells Gwen and a weakened Ben to get out while he clashes with Aggregor.

In the midst of the battle, Kevin's warehouse explodes for the second time, but Ben, Gwen and Kevin manage to escape while Aggregor escapes with Ra'ad during the blast. Now that Aggregor has all five of his prisoners, he's now able to resume transporting them to his home planet and carry out his plan of absorbing all of their powers and abilities.

Kevin and Gwen believe it's all over, but Ben tells them that he vows to use the powers of his five new aliens to save the prisoners and stop Aggregor once and for all.

Major Events

 * The team finally meet Aggregor face to face.
 * Ben obtains the Amperi DNA sample for AmpFibian.
 * Ben transforms into AmpFibian for the first time.
 * Aggregor recaptures Ra'ad, his fifth and final escaped prisoner.

Ultimatrix Alien Debut

 * AmpFibian

Characters

 * Ben Tennyson
 * Gwen Tennyson
 * Kevin Levin
 * Ra'ad
 * Bivalvan (cameo)
 * P'andor (cameo)
 * Galapagus (cameo)
 * Andreas (cameo)

Villains

 * Aggregor

Aliens Used

 * Jetray
 * AmpFibian (first appearance; fused with Ra'ad)
 * Brainstorm

Errors

 * When Ben selected Brainstorm, his hologram didn't have his brace.
 * In the end, when Ra'ad battled Aggregor, in one scene his eyes were seen red.
 * When Ben transformed into Ampfibian, his eyes were blue even though Ben had full control over it.

Trivia

 * A running gag in this episode is that Aggregor keeps busting the roof and Kevin complains about it.
 * Ra'ad's species is revealed in this episode.
 * Ben vows to use the five aliens' powers to save them; Ironically, he never actually uses their forms against Aggregor.