Chosen By The Sparks of Black

The gap between your control of ki and those without this is similar to the gap between the Heavens and Earth; you can flow overwhelming amounts of ki into your unarmed strike in the same trillionth of the moment of contact. When you score a critical hit, you land a Black Flash; you can use Stunning Strike for no ki cost, and your target has disadvantage on the required Constitution saving throw required for Stunning Strike. Additionally, your target takes an additional 2 rolls of your martial arts die in force damage as black lightning explodes from your unarmed strike, and you can make an additional unarmed strike (can be repeated to a limit equal to your Wisdom modifier).