Black Hand

You gather the powers of darkness into your fist and fling cold, dark flame at a target within range. Make a ranged spell attack.  On a hit, this spell siphons vitality from the target into you.  For the duration, the target has disadvantage and you have advantage on attacks, ability checks, and saving throws made with Strength, Dexterity, and Constitution. An affected target makes a Constitution saving throw (with disadvantage) at the end of its turn, ending the effect with a success.