Umbralation

As a bonus action, you form dark spinning sigils deep beneath the palms of your hands, as if black ink flows through your veins. These Umbralations cause shadows to swirl and cling to you, empowering your spells. Each time you damage a creature with a spell on your turn, you can add one d4 Necrotic damage to the total damage. A single creature can only take this additional damage once per turn.

When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d4 for each spell slot above 1st level.