Decay's Approach

A ray of sickly green energy lashes out toward a creature within range. Make a ranged spell attack against the target. On a hit, the target takes 2d8 necrotic damage and must make a Constitution saving throw. On a failed save, it gains 3 levels of  exhaustion for 1 minute.

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