Kingdom Hearts 3D: Dream Drop Distance
Lea requests to become a Keyblade wielder under Yen Sid in order to help Sora and Riku in their battle against Master Xehanort. Yen Sid accepts, but as they are short of time, has Merlin, Flora, Fauna, and Merryweather suppress the time needed for Lea to train. Lea eventually manages to summon the Flame Liberator, but does not get the hang of doing it reliably until after Sora has been rescued from Master Xehanort. Having learned to summon the weapon voluntarily, he playfully vows to become Riku's rival and a future Keyblade Master.
Kingdom Hearts III
Lea continues his training with his new Keyblade, learning how to Formchange it back and forth with his chakrams.
During his fight in the Keyblade Graveyard, Lea has his Flame Liberator broke by Xemnas. This briefly causes Lea to withdraw from the fight, until he is able to summon a repaired Flame Liberator to help hold off Kingdom Hearts.
The guard of the Flame Liberator resembles the Eternal Flames chakrams, as well as the guard of the Bond of Flame Keyblade, with a straight hilt rather than a cross-shaped handle. The blade and teeth take the shape of a glowing translucent streak of yellow-orange flames, resembling those of the Frolic Flame; however, the teeth of the Flame Liberator form the shape of a hook, rather than a closed loop. The Keyblade's chain links resemble the Eternal Flames; the token also resembles a pure silver version of the weapons.
Lea can Formchange the Flame Liberator into his chakrams at will.
The Flame Liberator's name references Lea's affinity for fire and his desire to free his friends from their fates.