Shadowform

You replace the target's body with mystic shadow material drawn from the Shadow Plane, rendering the target's physical form only quasi-real. Whenever a foe tries to directly attack the target of the spell (for instance, with a weapon or a targeted spell), that foe must attempt a Will save to disbelieve. If successful, the opponent can attack the target normally and is unaffected by shadowform for 1 round. If the foe fails, the target takes only one-fifth the normal amount of damage from the foe's successful attack or effect, and if the attack has a special effect other than damage, that effect is one-fifth as strong as normal (if applicable) or only 20% as likely to occur. Objects automatically succeed at their Will saves against this spell.