Taylor Swift will lord over season 17 of The Voice. In addition to the core four mentors on the show — Kelly Clarkson, John Legend, Blake Shelton, and Gwen Stefani — Swift will serve as a “mega mentor,” which sounds essentially like she will be coaching everyone at some point, with an emphasis on their Knockout Round numbers.

https://www.vulture.com/2019/09/taylor-swift-the-voice-mega-mentor.html