Bard's innate: Once per any unit’s turn, reroll any 1 die rolled by a unit within 2 hexes of you, including yourself.
Some skill results state that they must be resolved. However, you are still allowed to reroll them using the Bard's innate.
Remember that the Bard's innate only functions during unit turns, so any rolls that are made outside of battle or outside of a turn, cannot be rerolled with this innate.