Abominable Form( Elder Evils, p. 11)
You revel in the ruination of your flesh, drawing power from your disturbing deformities.
Willing Deformity (HH) ,
Living creatures with fewer Hit Dice than you that can see your undisguised form are afflicted by disgust. Each such creature must succeed on a Will save (DC 15 + 2 for each deformity feat you possess) or become shaken for a number of rounds equal to your Constitution modifier (minimum 1 round).
Your ghastly appearance grants you a +2 circumstance bonus on Intimidate checks.