Scry

The spell in question, is the one of the Witch Hired Sword called Scry. The description reads as follows:

Quote :

Scry: The Witch uses ancient diving crystals to foretell the future and influence the actions of her comrades.
For the duration of the turn one hero or henchman may re-roll D3 dice rolls and + or -1 to the result. Difficulty 6

We had a multiplayer game today with two players on each side. Me playing Dwarf Treasure Hunters and my friend playing Witch Hunters with me against a Druchii and a Beastmen Warband.

For maximum chance of a succesful Soulfire, I used my Scry spell on the Warrior Priest, potentially allowing him to re-roll and modify that re-roll with +1/-1, should he fail casting the prayer.

I cast Scry succesfully and allowed him 1 re-roll. He succeded the spell anyway, but before that, we had a short discussion about the 'OP-ness' of re-rolling 1 dice when rolling for difficulty on a spell. My opponent required that two dice had to be re-rolled, but I argued that it's not what the spell says - and it would be even more of a problem with only 1 re-roll avaliable, as I had on this try.

Which brings me to the question:
Would it be unfair to require atleast two re-rolls to be able to re-roll and modify a prayer/spell difficulty roll, or can a single dice be re-rolled and modified?

The killer as far as 'fair' is the added ability to add or subtract 1 from the re-rolled die as far as I'm concerned.  We had always managed to not read that far and being a forgetful lot, rarely used our re-rolls.  One guy with a good memory cleaned up on us with his witch.

But anyway, there are other items that allow one die to be re-rolled so I do not think it 'unfair' for one re-roll to be allowed when casting a spell.  

If I were in a house-ruling mode, I would get rid of the + or - part of the rule and allow D3 re-rolls to be used as the player chose.