Death Line

You attempt to drain the life force from creatures in a line 20 feet long and 5 feet wide in a direction of your choice. Each creature in the line must succeed on a Constitution saving throw, taking 3d8 Necrotic damage on a failed save and half as much on a successful one. If at least one of the creatures caught in the spell fails their save, you gain 1d8 temporary hit points. 
For each level cast above 2nd, the damage increases by 2d8, and you gain an additional 1d8 temporary hit points.