Requirement(s) Nidal
Numerous expeditions to accursed regions like Nidal’s Finder’s Gulch have reinforced your already steadfast faith. Once per day, you may reroll a Will saving throw made against an attack or effect that originates from an undead creature. You must decide to use this trait after the first saving throw is rolled, but before the results are revealed. You must take the result of the second roll, even if it is lower.
Anyone notice that Finder's gulch is in Isger?
there are (at least) 3 cannon sources to indicate that this location is in Isger:
ISWG page 84, seven days to the grave page 83, and fey revisited page 44.
The feat does use the world like.