D&Dtools1

You reshape your personal fate to potentially avoid some tragic action, but the ripples caused in your destiny have unpleasant side effects for a brief period.
After learning the result of a saving throw that you have rolled, you may cast this spell to reroll the save, but with an insight bonus equal to your caster level (maximum +20).
Alternatively, if you are struck in combat you can apply the insight bonus to your AC against the attack (even if flat-footed); if your new AC exceeds the attack roll, the attack misses you.
Casting this spell has a side effect: until the start of your next turn, you take a -4 penalty on all saving throws and to your AC.