Blade of Sacrifice

You evoke a cruel sacrificial blade in your free hand. The blade is similar in size and shape to a scimitar, and it lasts for the duration. If you let go of the blade, it disappears, but you can evoke it again as a Bonus Action.

As an action, you can make a melee spell attack with the sacrificial blade. On a hit, the target takes slashing damage equal to 4d6 plus your spellcasting ability modifier.

Whenever you reduce a creature to 0 hit points with the blade, if that creature was grappled, prone, or restrained, you regain health equal to the damage dealt and the damage of the blade increases by 1d6. This effect cannot stack

Using a Higher-Level Spell Slot. The attack damage and damage bonus each increase by 1d6 for each spell slot level above 3.