Aurifar, the Caliph of the Sky, has judged you, and he now shows you special favour.
Prerequisites: Patron deity Aurifar, must have survived at least three days in the waste without water.
Benefit: You gain a +2 sacred bonus on Constitution checks to avoid the negative effects of thirst (see Dehydration, page 15). You gain a +2 sacred bonus to your Armour Class against undead creatures that are adversely affected by sunlight, such as vampires and wraiths.
Cleric is now an additional favoured class for you; the cleric class does not count when determining whether you take an experience point penalty for multiclassing.
Special: Your aura shows faint abjuration magic. If you ever lose favour with Aurifar, or change your patron deity to another deity, you lose the benefit of this feat, and you immediately begin experiencing the effects of thirst as though you had gone without water for one week. You do not gain a replacement feat. If you later return to Aurifar’s faithful and receive an atonement spell, you regain the benefit of this feat.
Source: Sandstorm (Page 50)