The Fool's Coin

You use magic to imbue a coin with fate then flip it. As with all things involving fate you must take the first step. You must call which side it lands on, if correct you add 1d6 to a attack roll or ability check. If you are wrong subtract 1d6 to a attack roll or ability check or damage. After determining the result of the coin flip, the coin then flashes out out of existence. 

You can use higher level spell slots to increase the number of d6 you roll, i.e using a 2nd level spell slot increases it to 2d6.