From your earliest days, you were destined to sacrifice everything in your quest for power.
Prerequisite: You must have had friendly contact with an evil-aligned outsider that would qualify as a challenging foe, have a fiend-related sorcerous bloodline such as abyssal or infernal, have direct fiendish ancestry (such as being a tiefling or half-fiend), or have the Fiend Raised or The Fiend background.
Benefit: You gain a +2 bonus on Charisma-based checks involving evil-aligned outsiders and +1 bonus to the DC of spells and spell-like abilities you use against such creatures. You take a —2 penalty on Charisma-based checks involving good-aligned outsiders.
Goal: Successfully trade your soul to an evil outsider.
Completion Benefit: You gain a +2 enhancement bonus to an ability score of your choice. This enhancement bonus can't be dispelled or removed save by the direct intervention of a deity, and counts as a supernatural ability. In addition, you gain a +2 bonus on caster level checks (including dispel checks and checks to bypass spell resistance) against good-aligned outsiders. If you die while under the effects of this agreement, you can't be brought back from the dead unless the evil outsider permits it. You lose your completion benefits immediately and permanently if you renege on the arrangement by which you traded your soul, though you keep the feat's basic benefits.