Theory is a Rare Blade in Xenoblade Chronicles 2. She can grant tremendous power to her Drivers, Rex, Nia, Zeke, or Mòrag, and their allies. Theory uses the ice element, wields a Chroma Katana, and acts as a Tank in battle. She moves as a skater on ice with an elegance reminiscent of a fairy, similar to Praxis, a female Blade with whom Theory shares a bond.
Theory is first met as a quest-exclusive Blade boss during the "Crystal Clear" quest, where she is refered to as Plunderous Theory. She is fought at level 33 on Obra Street in Torigoth alongside Piratical Praxis. She is fought a second time at level 48 as a quest-exclusive enemy during the "Pest Control 3" quest where she is refered to as Mediator Theory, alongside a group of Cherys Medooz in the Lud Cloudway: Fonsett of the Leftherian Archipelago.
