Crurorwhip

You create a whip out of your own blood in your free hand. By expending 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 the 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 2nd level or higher, the damage increases by 1d6 for each slot level above 1st.