Thrall To Demon

Type: Vile
Sources: Book of Vile Darkness
Champions of Ruin
Fiendish Codex I

You formally become a supplicant to a demon lord. In return for your obedience, you gain a small measure of that demon lord's power.
Prerequisite: Chaotic evil alignment.
Benefit: Once per day, while performing an evil act, you can call upon your demonic patron and gain a +1 luck bonus on any one attack roll, saving throw, ability check, skill check, or level check.
Special: You can take this feat only once. If you take it, you cannot take the Disciple of Darkness or Scion of Sorrow feats, which link you in a similar way to powerful archdevils or yugoloth lords.