Corrupted Smite

The target hit by the strike takes an extra 2d6 Necrotic damage from the attack. The target must succeed a Constitution Saving Throw with a DC equal to your spellcasting save DC.If they succeed the Saving Throw, they receive half damage. If they fail thee saving throw, they take full damage and, until the spell ends, the target has Disadvantage on all attack and damage rolls made by it.

Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 2.