Devil True Names and Infernal Sigils

Knowledge of a devil's true name or the ability to inscribe its sigil grants significant power over the fiend. In the cast of the spell planar binding, when a devil's true name is used to conjure a specific fiend, the target devil takes a -5 penalty on the initial Will save to resist being summoned; if its sigil is inscribed within the magic circle binding it, the devil takes a -5 penalty on all checks to escape the circle. True names and sigils might also be known to have other powers over devils, though most