Blood for blood

A spectral wound carves itself into your wrist, drawing forth a thin stream of blood. You take 1d4 Necrotic damage. This damage bypasses any Resistance or Immunity you have, and it cannot be reduced or absorbed by Temporary Hit Points. Then, you make a Concentration check to determine if the pain distracts you from the spell's focus. Once this blood price is paid and only if you suceed the Concentration check, point the finger of your bloodied hand toward a creature you can see within range, other than an Undead or a Construct. The target must make a Wisdom saving throw. On a failed save, the target takes 2d6 Necrotic damage. On a successful save, it takes half as much damage. You then regain a number of Hit Points equal to half the Necrotic damage the target took, rounded down.

As a Bonus Action on your subsequent turns while you maintain Concentration, you can repeat this effect, taking 1d4 Necrotic damage again to target a creature within range.

Using a Higher-Level Spell Slot. When you cast this spell using a spell slot of 2nd level or higher, the damage dealt to the target increases by 1d6 for each slot level above 1st. The damage you take to cast or maintain the spell increases consequently by 1d4 for each slot level above 1st.