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Trade Off is the thirty-sixth episode of Ben 10: Alien Force.


The episode begins with Darkstar studying in a warehouse when Kevin breaks in. Kevin wants to send Darkstar into the Null Void, but Darkstar quickly defeats him and says that he wanted Kevin to find him due to the fact that both of their lives depended on it.

Darkstar releases Kevin on the condition that he listens and he says that he has discovered an artifact called the Dominus Librium that will transfer their energy in order to make both of them normal and neutralize their powers. However, it is on an island and he needs Kevin to help him retrieve it. Afterwards, Kevin agrees to help Darkstar. Meanwhile at Ben's house, Ben and Gwen try to call Kevin but he doesn't answer. Ben transforms into Jetray and he flies with Gwen to a mission. Darkstar and Kevin arrive at the island in a hovercraft and enter into the temple where the artifact is located and it is flanked by ugly statues. Kevin triggers a booby trap that brings the statues to life and they attack him and Darkstar. Kevin and Darkstar fight with them and retreat. They enter into the temple. The statues are too large to follow them. While they are inside, Kevin and Darkstar discovered the Dominus Librium and Darkstar tries to retrieve it, but it is protected. Kevin goes up to it and is able to take it. Kevin is closed in two enormous hands of a statue surrounding the Dominus Librium.

Darkstar frees Kevin, who has the Librium. The temple starts to collapse and Kevin and Darkstar run, while barely escaping, and evade the statues. The island floods as Darkstar and Kevin get into their hovercraft and fly away. They enter into an isolated spot and use the Dominus Librium. The Dominus Librium works on Kevin and Darkstar and they are transformed back into normal, although their powers are gone. Then, Darkstar punches Kevin, takes the Dominus Librium, and tells him to stay away from him. That night, Kevin arrives at Ben's house and presents that he is human and powerless. Gwen is concerned about Kevin's black eye, but he lies about it. The team drives to a warehouse to fight the Forever Knights. Gwen tells Kevin to wait outside due to the fact that his lack of powers makes him a liability. While inside, Ben tries to transform into Humungousaur, but he transforms into Big Chill instead. Big Chill and Gwen fight the Forever Knights and Kevin comes inside and fights them as well. The Forever Knights attempt to flee, but Big Chill freezes their truck and transforms into Ben. Kevin reveals that he sabotaged the engine and Ben admits that Kevin is still an important part of the team. Later, Kevin asks Gwen to do something with him, but she senses Darkstar in his aura and declines.

Michael absorbing Gwen's powers once again

Gwen tracks Darkstar to the warehouse and enters inside. As Michael Morningstar, he explains the Dominus Librium to Gwen and reveals that he is using it as a substitute for his powers. Michael tries to absorb Gwen as Ben tries to contact Gwen, but he is unable to. Kevin tells Ben about his deal with Darkstar and Ben becomes angry and decides to go search for Gwen. Ben tries to transform into Jetray again to search for Gwen, but he transforms into Echo Echo instead and makes an army to split up, but Kevin knows where to go and the Echo Echoes get in the car. Echo Echo transforms back into Ben and they drive to the warehouse as Gwen fights Michael. Michael absorbs her shots with the Librium and finally grabs her with the Dominus Librium. As Michael starts absorbing her power, Ben and Kevin arrive and Ben transforms into Swampfire and attacks Darkstar, but his attacks have no effect on Michael. Darkstar absorbs Swampfire as well, but Kevin steps in front of the Dominus Librium and grabs it in order to send all of the energy back where it belongs and mutating him and Darkstar again. As Darkstar runs away with the destroyed Dominus Librium, Gwen and Kevin help Ben up and they go to Mr. Smoothy.

Noteworthy Events

Major Events

  • Darkstar returns and makes an offer to Kevin that will help them return to their original forms, only for both of them to revert back to their mutated forms.



Aliens Used



Darkstar: Can't you feel it? The Librium is transferring your excess energy into me.

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Kevin: It... hurts!
Darkstar: Nothing... worth having is gained... without effort!

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Ben: Then I guess it's time for... (tries to transform into Humungousaur, But, he transforms into Big Chill instead) Big Chill!? (groans) Never what I ask for. Never!

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Ben: The fastest way we can track down is as Jetray, so.... (attempts to transform into Jetray, but, transforms into Echo Echo instead) Echo Echo?!

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Gwen: (To herself) Michael's mana led me to him like a beacon. He's inside, I can feel it. (Makes steps out of mana and walks over fence and enters Michaels lair ready to fight)
Michael: (Sees Gwen in mirror from admiring his face) Ah, lovely Gwen. I've been expecting you.
Gwen: I'll just bet you have. Kevin's aura stinks of you. Tell me what you did to him and maybe I'll go easy on you. (Mana's color gets more intense)

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Swampfire: SWAMPFIRE!!!! Hey, the Omnitrix got it right this time!

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Naming and Translations

Language Name Origin
French Le Marché The Trade
Hungarian Indítsd a Frekvenciát Start the Frequence
Polish Coś za Coś Something for Something
Portuguese (Br) A Troca The Exchange
Romanian Dublura Duplicate
Spanish (HA) El Intercambio The Interchange
Spanish (Spain) Intercambio Interchange


Voice Actor Role(s)
Yuri Lowenthal Ben Tennyson
Ashley Johnson Gwen Tennyson
Greg Cipes Kevin Levin
Dee Bradley Baker Jetray
Big Chill
Echo Echo
Knight Leader
Wil Wheaton Darkstar


  • The plot of this episode, mainly Kevin's role, is similar to The Thing from the 2005 Fantastic Four film, in which The Thing is assisted by Doctor Doom in reverting to normal from a disfigured form, but decides to re-mutate himself in order to save his friends from the same villain.
  • Barrymore Theatrical Supplies is a nod to the Barrymore acting family, whose members include Lionel Barrymore, John Barrymore, and Drew Barrymore.
  • The Witch-King of Angmar's mask from The Lord of the Rings: The Return of the King is seen in a couple of shots at the warehouse.


  • Jetray's hologram faces away from Ben.
  • When Ben turns into Jetray, the two black stripes on his shoulders are missing for a few frames, just before he picks Gwen up from the ground.
  • When Ben says to Darkstar, "You may look human again," his mouth doesn't move.
  • When Swampfire appears, his Omnitrix symbol looks flat and lacks the rim.



T.J. Collins

Ben 10: Alien Force Episodes