Sphere of Entrapment

When cast, a translucent sphere appears around an opponent spellcaster. It looks and functions much like a minor globe of invulnerability, but has the properties of both that spell and its reverse. Unless the wizard or priest makes a successful saving throw vs. magic, the slightly shimmering sphere takes form around him and remains for 4 rounds. Once inside the sphere of entrapment the wizard can't physically leave its confines. If he casts any spells of 1st- through 3rd-level, the effects of the spell are turned back upon him, as if they had rebounded off the inside of the sphere.

While the wizard is so confined, no spells of 1st through 3rd level from the outside can harm him, bouncing off the outside of the sphere just as if the wizard were protected by a minor globe of invulnerability. The sphere has no effect upon spells of 4th level or higher from within or without. The sphere may be entered physically at any time by those wanting to engage the trapped wizard in melee. It has no effect on magical weapons, nor on magical items which produce effects which would be of 4th level or higher. A trapped wizard might be able to use a wand or ring depending on the spell effects they produced. Should the trapped wizard utilize an anti-magic shell or globe of invulnerability or should another wizard with either of these spells cast upon himself enter the area of the sphere of entrapment, the sphere is immediately dispelled.

The material components for the spell are a crystal bead and a drop of the caster's blood, which is smeared on the bead as the spell is cast.