Power Modifier Value: -10%
Your abilities are driven by trained magic and your personal vision of the Discipline you are following. Work with your GM to develop a code of behavior appropriate to your Discipline comparable to a -10 point Vow, Code of Honor, or similar disadvantages - see assorted Earthdawn sourcebooks for details (in particular, search for the term "Talent Crisis"). If you violate this code, you may suffer from temporary penalties to the dice rolls and levels of your individual ability ranging from minutes to days or until you "atone" for your transgression, depending on its severity. Furthermore, extremely powerful entities such as Great Dragons or the strongest of Horrors may also be capable of weakening your abilities.
Statistics: The personal code of behavior is essentially a "Pact with the GM" (see GURPS Powers, p. 104), though reduced to half its value because it can only weaken abilities, not stop them from working entirely. The existence of anti-powers (however rare) adds another -5%. The Earthdawn setting assumes that mana/magic exists everywhere, and even though the mana might be corrupted by a Horror, this doesn't disrupt ordinary discipline abilities. In settings where mana is not ubiquitous and areas where magic itself is weakened or absent (such as in the Shadowrun setting), a further -10% should be added to the Power Modifier and all ability costs adjusted accordingly.
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