Critical Strike

Once per turn, when you attack with any type of attack, as a bonus action, you can flip a coin and call out the result (e.g. you flip a coin and you call out heads). if the result you called out is the outcome (e.g. you called out heads and it landed on heads) the attack automatically hits and counts as a critical hit and does double damage. if the result you called out wasn't what the outcome was (e.g. you called out heads and it landed on tails) you automatically fail that attack and you get dealt the damage (e.g. if the attack was a firebolt spell, you would roll the dice and the damage is dealt to you)