Way of the Wicked
There is one method of outsider coercion that helps guarantee that a binder can bargain from a position of relative security. Many spellcasters believe that a true name is inscribed on the essence of every creature, a secret word that describes it so perfectly and utterly that to speak the name is to define the being. For mortals, this name is buried in the soul, hidden away from prying and dangerous eyes. Outsiders’ true names take the form of sigils carved upon their very essence. In Hell, these sigils change as the devil changes in stature, and some that may once have held power over certain devils have become outdated. It is said that some outsiders have assumed names and that they use the aliases to lure foolish mortals into using for summoning; the outsider pretends to be under the control of the binder, but merely bides its time before it strikes.
To discover a single outsider’s true name, a spellcaster must spend at least a month in a library or on a quest of discovery to uncover occult mysteries and riddles hidden in the pages of books, scrolls, and glyphs written millennia ago, buried in ancient temples or found among the ravings of madmen’s spellbooks. At the end of this month, the GM makes a Knowledge (planes) check for the character. The DC is 10 + the creature’s Hit Dice. The GM can increase the DC by +2, +5, or even +10, based on the power of the outsider or the circumstances of the true name search. A failure by 5 or more turns up false information that may expose researchers to unexpected dangers. For most outer-planar outsiders, knowledge of the creature’s true name is a powerful weapon. In summoning, if the name is spoken correctly (requiring knowledge of at least one of the outsider’s languages, or a Linguistics skill check with a DC equal to 10 + the creature’s Hit Dice), the target takes a –5 penalty on the Will save to resist being conjured, and if its name is inscribed in the protective magic circle, the outsider takes a –5 penalty on all checks to escape or breach that circle.
For elementals (including geniekind), such true names are not binding as they are for fiends and other outsiders, and do not give the creature a penalty to its Will save to resist being summoned. However, if the caster speaks the true name of the elemental, the elemental will most likely be intrigued enough to listen—a wizard with power and cunning enough to find an elemental’s true name is a wizard with guile and strength, and elementals treasure these qualities.
Not all outsiders have true names. The chaotic and primeval nature of proteans defies the strange logic of true names, as does the writhing chaotic nature of the qlippoth. It is unclear whether aeons have true names. There are those sages who believe each aeon has two true names, and only by finding out both names can a creature gain some control over the aeon, but such matters are purely conjecture.