The Indomitable Soul feat (PHB II, p. 80) grants the following benefit:
Benefit: Whenever you make a Will save against a mind-affecting or fear ability, you can roll 2d20 and use the higher of the two die rolls.
Meanwhile, the Pride domain allows rerolling natural 1s:
Whenever you roll a 1 on a saving throw you may immediately reroll the save. You must keep the result of the second roll, even if it results in the roll of another 1.
And it is not clear to me how those two interact:
- A player rolls two 1s, they are allowed to reroll each 1 (independently), then pick the higher roll.
- A player rolls two 1s, pick the highest result (a 1...), they are allowed to reroll it, and roll two dies again, picking the highest result.
- A player rolls two 1s, pick the highest result (a 1...), they are allowed to reroll it, and roll a single die, keeping its result.
- Something else?
For bonus points, what about the interaction with abilities allowing rerolls on a failed save (not only one a roll of 1). An answer that can manage to cover rerolling generally would be better than one that fixates on the particulars of the Pride domain, though that is the main focus.