From Gamesverse Wiki
Barrier Jackets are a class of spells used by combat mages as defense and utility during combat. They are in many ways similar to Jackets, inasmuch as they consist of usually-invisible magical fields that provide the spell's utility, combined with illusions that duplicate some form of ordinary clothing. Barrier Jackets provide much greater functionality, and hence require greater magical capacity, than ordinary Jackets.
The major function of a Barrier Jacket is as armor against attack, whether physical or magical. This function can remain active as an invisible field even when the illusionary clothing is deactivated, allowing for some degree of stealth. For a powerful mage, a Barrier Jacket will render them invulnerable to most purely physical attacks below the anti-armor level. In fact, Barrier Jackets are responsible for the majority of the resilience mages display in combat; intentionally disempowering the Barrier Jacket in order to allow greater power to other spells is noted as a very risky move, which would make many ordinary battlefield attacks instantly fatal should they connect.
As secondary functions, Barrier Jackets are capable of shielding the user against pressure differentials and providing them with breathable air. This allows them to act as environment suits for environments as diverse as outer space or the deep ocean. They also incorporate such defensive measures as anti-flash visors and radiation shielding.