All or nothing

five times per day, instead of rolling a d20, you can flip a coin. Heads = critical hit; tails = critical fail. Must be used at least once a day. When you get a consecutive results whether positive or negative you gain benefits or detriment to your next roll of a D20. After two you get a advantage/disadvantage to your next roll, After three you get +5/-5 to your next roll, after four a critical pass/fail is lowered or increased by 4 . After five you can choose to succeed within the next 10 rolls (attack rolls only count as one no matter how many you roll), If it is five fail the choice goes to the dm.