Magnesia (マグネシア Maguneshia ) is Fecor's signature Power of Unrestraint, which creates a storm of heavy cubical particles. These particles are controlled at Fecor's will. Its streams inflict heavy blows upon the enemies in spite of its true purpose as a defensive maneuver. They can also be concentrated to form giant objects to crush Fecor's enemies.
Magnesia looks like a group of grey particles combining to form something. When they drop, they look like multiple brown cubes, or an extremely large cube.
Magnesia is used to protect the Divine Gate when the Flame Haze Army tried to stop the return of the Snake of the Festival. It is easily cut by Tenmoku Ikko with the Nietono no Shana when Fecor tries to use it to defend himself when Shana summons Tenmoku unintentionally.