Just published it for Pathfinder, so let’s publish it for DnD 5e
Casting Time: 1 action
Range: 150 feet
Components: V, S, M (a piece of a ghoul’s heart)
You condense your hatred for life through the ghoul’s heart and force it out into the world as a 20-foot radius blast centered on a creature in range. Each creature in the sphere must make a Constitution saving throw. A target takes 6d6 necrotic damage on a failed save, or no damage on a successful one.
The life you destroy comes back to you as you feast as a ghoul on life. You heal damage equal to half the total damage done by this spell.
At Higher Levels: When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.