When this spell is cast, an invisible barrier before the front of the magic-user comes into being. This shield will totally negate magic missile attacks. It provides the equivalent protection of armor class 2 against hand hurled missiles (axes, darts, javelins, spears, etc.), armor class 3 against small device-propelled missiles (arrows, bolts, bullets, manticore spikes, sling stones, etc.), and armor class 4 against all other forms of attack. The shield also adds +1 to the magic-user’s saving throw dice vs. attacks which are basically frontal. Note that all benefits of the spell accrue only to attacks originating from the front facing the magic user, where the shield can move to interpose itself properly.