Blood Dart

Roll a d4, and take the DMG shown as you use the Dagger to draw your own blood and form it into a crystallised dart, which you then fling at an enemy within range. Roll to hit. They then take 1d6 + your spellcasting attack Necrotic DMG.

After dealing damage, roll a CON check against your own Spell Save DC. On a success, you regain half the DMG dealt by this attack in HP.