Gwen Tennyson/BTEF

Gwen Tennyson is a main character in the series Ben 10: Eternal Forms.

History (Pre-BTEF)
See Gwen Tennyson.

History (BTEF)
When Kevin went insane from absorbing the energy of the Ultimatrix, Gwen resorted to desperate measures. She used a spell that transferred his insanity into her, which saved him, but also caused her to transform into her full Anodite form and completely lose her humanity and her moral code. Knowing this would happen, she also drank a potion that would cause her to die in eight hours. While in this altered state of mind, Gwen brutally murdered a Forever King and Zombozo, and would have taken Animo's life as well if Ben, Kevin and Verdona hadn't stopped her.

Ben, with Verdona's help, transferred both the poison and the insanity into himself before Gwen could be killed by it. As a result she survived, but was still at risk of losing control and going mad with power naturally. To counter this, Verdona gave Gwen the Training Collar. This allowed her to stay sane, although it was too late for her to recover her human form.

In Nuclear Dropout, Gwen was kicked out of her school due to her alien form being a “distraction to the rest of the class”. She continues to be bitter about it.

Powers and Abilities
Although she is in full Anodite form, due to the Training Collar, Gwen is actually weaker power wise than she was as a human. She is limited to how much mana she can manipulate at one time, causing the creation of more massive constructions, such as large shields and dense energy beams, impossible. She also has difficulty tracking long distance, and cannot cast energy intensive spells such as teleportation. If she increases this limit, which is usually set as 3, she runs the risk of unknowingly sucking the auras of her loved ones dry, and on higher settings losing her mind.

On the other hand, her forms gives her many abilities that she lacked as a human. She is able to tirelessly levitate off the ground, and fly higher for long periods of time before tiring. She has great control over her energy hair, able to use it for whipping, or as extra appendages. She is much more in tune with the energies around her, and is able to tell immediately if something isn't right.