Bit of Luck (Sp): You can touch a willing creature as a standard action, giving it a bit of luck. For the next round, any time the target rolls a d20, he may roll twice and take the more favorable result. You can use this ability a number of times per day equal to 3 + your Wisdom modifier.
I've been using this power a heap lately and the way I've been doing it is declaring that I'm using bit of luck for a particular roll and simultaneously rolling two die for a result.
On closer inspection I'm rethinking/considering how many other ways it's possible to use this, some seemingly more dubious than others.
So what would be the correct way to interpret, bit of luck's rolling?
1: Declare bit of luck on roll, roll twice simultaneously
2: Declare bit of luck, only roll again if first roll unfavourable. Can use bit of luck on saves in following round if unused.
3: No need to declare bit of luck, anytime in following round roll again on a unfavourable roll.
Obviously a very powerful ability, making fails very hard to do. Additionally with the domain's 6th level power:
Good Fortune (Ex): At 6th level, as an immediate action, you can reroll any one d20 roll you have just made before the results of the roll are revealed. You must take the result of the reroll, even if it's worse than the original roll. You can use this ability once per day at 6th level, and one additional time per day for every six cleric levels beyond 6th.
It also implies a failed bit of luck, can be rerolled too!