Hellscarred (3.5e Feat)
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Having had your mind or body twisted by the essence of a fiend, you have gained some sensitivity and immunity to their power.
Prerequisite: Must have failed a saving throw to a spell or effect associated with a fiend, and cannot be a fiend or have any feats with the [Fiend] subtype.
Benefit: If you ever fail a save to a Special attack, Special Quality, or spell of a fiend, you may a reroll that save (once per save). This ability may be used a number of times per day equal to your Charisma modifier (minimum 1). In addition, you may cast detect fiends as a spell like ability at will. This spell functions as enlarged detect magic (120 foot range), but it only detects the presence of fiends and their magical effects. This effect also cannot determine school of magic, but instead will indicate the race of the fiend (baazetu, tanar’ri, yugoloth, or demondand subtype if appropriate).