The Magic Barrier Spell is a spell that creates a barrier of magic energy around the user as a means of protection. The strength and duration of the barrier is dependent on the skill of its caster.
This spell was used in The Enchanted Parade by Diana and Professor Finnelan to protect themselves from the poison of the mushroom monster that Akko and Sucy accidentally created during the class.
This spell was used by the Minister Dorlin to avoid the residue of the explosion caused by the potion of some students during the Samhain Festival.
Ursula uses this spell to protect herself from the energy attack of the sentinel statue guarding Croix's lab in the New Moon Tower. In making the powerful barrier her hair turns its natural red, which is possibly related to when she cast "Palais Capama" in The Fountain of Polaris.