You gather the powers of darkness into your fist and fling dark, paralyzing flame at a target within 30 feet. If you make a successful ranged spell attack, this spell siphons vitality from the target into you. For the duration, the target has disadvantage (and you have advantage) on attack rolls, ability checks, and saving throws made with Strength, Dexterity, or Constitution. An affected target makes a Constitution saving throw (with disadvantage) at the end of its turn, ending the effect on a success.