Crimson Edge

You draw blood from your palm and coat your weapon or spell-focusing hand in it, shaping it into a glowing crimson edge.
Until the spell ends, once on each of your turns when you hit a creature with a melee weapon attack or a spell attack within 10 feet, the attack deals an extra 1d6 necrotic damage.

Each time you deal this extra damage, you take 1 point of necrotic damage as the edge feeds on your life.

If you reduce a creature to 0 HP while this spell is active, you regain hit points equal to your Constitution modifier.

At Higher Levels.

When you cast this spell using a spell slot of 2nd level or higher, the extra necrotic damage increases by 1d6 for every two slot levels above 1st (2d6 at 3rd, 3d6 at 5th, etc.).