You utter a unholy word, and dark energies flow from your fingertips and seep into the skin of a creature you touch. Make a melee spell attack against the target. You have advantage on the attack roll if the target is not at full health. On a hit, the target takes 1d8 necrotic damage and has disadvantage on all attack rolls made until the end of it's next turn.

The spell’s damage increases by 1d8 when you reach 5th level (2d8), 11th level (3d8), and 17th level (4d8).