You could borrow hero points from Pathfinder. Basically, each player gets one or two hero points at the beginning of the session and can spend it to reroll a d20 at any point in the night. You take the rerolled result. Note that these expire at the end of the session and cannot be stacked up for next time.
You could borrow hero points from Pathfinder. Basically, each player gets one or two hero points at the beginning of the session and can spend it to reroll a d20 at any point in the night. You take the rerolled result. Note that these expire at the end of the session and cannot be stacked up for next time.