A voice meant to be that of Gwen Tennyson is heard in Avatar Aang Vs. Ben Tennyson, provided by Toby Navarro. She says the line "When Wildmutt mauls her like a platypus bear!" over the unintelligible growls of Ben Tennyson in the form of Wildmutt at the end of his second verse. This references a moment in the series where Gwen announces Wildmutt's name "for" Ben, of whom it is typical to call out his alien forms' names when turning into them, upon a transformation due to Wildmutt being unable to speak.
Gwen was also mentioned by Zuko when he says that Ben is "way too close with his cousin", implying incestuous shipping.
Information on the Cameo
Gwen Tennyson is the deuteragonist of the Ben 10 series and Ben Tennyson's cousin. Initially a smart, sassy supporting character with no "special powers", she later learns sorcery, her capacity to do so being revealed later still as due to her being part–alien. She has also been made as Kevin 11's love interest.