Anti-magic Shield

The caster summons a spherical barrier 30 feet in radius that is centered on the glass sphere. All magic that attempts to pass through the barrier is scattered. When magic is scattered, roll a d10. If the roll is 9 or 10, the magic passes through with its effects halved. If the roll is 8, the magic passes through unimpeded. Otherwise, the spell is dispersed into the air around the barrier. Scattered spells still count as active and will still effect the area around the barrier. The barrier lasts for 3 hours on its own and can last longer if the caster maintains concentration.