Pyra summons Rex, who says "Do it, Pyra!" and performs an overhand slash to transition into a cutscene. In the cutscene, Pyra says "Yeah, on it.", and she and Rex hold the Aegis Sword together and leap toward the trapped opponents, shouting the move’s name. The game then transitions back into normal gameplay, where Pyra and Rex summon a large pillar of fire in front of them, which then explodes. Pyra says "Witness our power!" at the end of the Final Smash.
In Xenoblade Chronicles 2, Burning Sword is Pyra's Level 4 Blade Special. The technique also serves as one of Pyra's signature moves, as she and Rex perform Burning Sword during many cutscenes. The move's animation in Smash is a recreation of its animation in battles in Xenoblade Chronicles 2.