Weathering Strike
Necromancy cantrip (Cleric, Sorcerer, Warlock, Wizard)
Casting Time: 1 action
Range: Self
Components: S, M (a weapon with which you have proficiency and that is worth 1+ CP)
Duration: Instantaneous.
You make one attack with a weapon you are wielding. You can use your spellcasting ability instead of Strength for the attack and damage rolls. On a hit, the target suffers the weapon attack's normal effects. If the attack deals damage, it can be Necrotic damage or the weapon's normal damage type (your choice).
Until the start of your next turn, the target cannot regain hit points. A creature immune to Necrotic Damage is immune to this effect.
Cantrip Upgrade: The attack deals an extra 1d6 Necrotic damage to the target on a hit when you reach 5th level, 2d6 at 11th level, and 3d6 at 17th level.