Arterial Drain

You rip the blood you crave from your enemies’ veins to sustain yourself. All targets in a 15 ft. cone must succeed on a Constitution saving throw or take 2d6 necrotic damage. If a target is already damaged, they instead suffer 2d8 necrotic damage on a failed save. You regain 1d4 hit points for every target that fails their Constitution saving throw. On a successful save a target takes only half damage and you do not receive any healing from them. 

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d6 (1d8) for each slot level above 1st.