Cruorwhip

You create a whip out of you own blood in your free hand. By spending a number of hit points, you create a whip similar in size and shape to a normal whip. If you let go of the whip, it disappears, but you can recreate it again as a bonus action. You can use your action to make a melee spell attack with the whip. For every 5 hit points spent in casting of this spell the reach increases by 5 feet, with a minimum health cost of 5 hit points. On a hit, the target takes 2d6 necrotic damage. 

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases to 3d6. When you use a spell slot of 5th level or higher, the damage increases to 4d6. When you use a spell slot of 7th level or higher, the damage increases to 5d6. When you use a 9th level spell slot, the damage increases to 6d6.