A flash of green energy streaks toward a creature of your choice within range. Make a ranged spell attack against the target. On a hit, the target takes 4d6 necrotic damage, and the creature's next attack roll has disadvantage as the negative energy surges through their body. 

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