Dusk Strike

You brandish the weapon used in the spell's casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack's normal effects and it can't regain hit points until the start of your next turn, it is also sheathed in shadows until the start of your next turn.

If another hostile creature goes within 5ft of the first creature while it is under the effects of this spell or ends it's turn there, it takes necrotic damage equal to your spell casting modifier. This spell's damage increases when you reach certain levels.

At 5th level, the melee attack deals an extra 1d8 necrotic damage to the target on a hit, and the necrotic damage to the second creature increases to 1d8 + your spellcasting ability modifier. Both damage rolls increase by 1d8 at 11th level (2d8 and 2d8) and 17th level (3d8 and 3d8).