AD&D 2nd Edition

When this spell is cast, an invisible barrier comes into being in front of the wizard. This shield totally negates magic missle attacks. It provides the equivalent protection of AC 2 against hand hurled missiles (axes, darts, javelins, spears, etc.), AC 3 against small device-propelled missiles (arrows, bolts, bullets, manticore spikes, sling stones, etc), and AC 4 against all other forms of attack. The shield also adds a +1 bonus to the wizard’s saving throws against attacks that are basically frontal. Note the these benefits apply only if the attacks originate from in front of the wizard, where the shield can move to interpose itself.