Even with magick evasion, shields never block status effect spells. Shield Block augments add +5% to both physical and magickal evasion per augment purchased (as long as the shield provides both; if a shield only offers physical evasion the augment boosts affect only that). Some enemies have Ignore Evasion as a passive ability, which makes using shields pointless. The player can gain the same ability by equipping the Cameo Belt. FFXII IZJS