The Gamble

You choose a ceature you can see and then decide how much HP do you want to Bet, and then you a D20 with no modifiers, if the die is 10 or lower you lose and conversely if the roll 11 or higher you win. If you win then you deal necrotic damage to your target equal to your Bet amount and if you lose then you deal necrotic damage to your self equal to the amount you Bet.