Windy Shield

封気結界呪／風結呪（ウィンディ・シールド） Surrounds the spell-caster with a barrier of wind which defends the caster from all attacks. The most popular defensive spell. It is possible for several spell-casters to combine their shields to increase the defense of the barrier and it can be used against all offensive spells. The only problem is that concentration is necessary when this spell is cast, so other spells can not be cast while maintaining the shield.