Melf's Acid Arrow

A shimmering green arrow streaks toward a target within range and bursts in a spray of acid. Make a ranged spell attack against the target. On a hit, the target takes 4d4 Acid damage and 2d4 Acid damage at the end of its next turn. On a miss, the arrow splashes the target with acid for half as much of the initial damage only.

Using a Higher-Level Spell Slot. The damage (both initial and later) increases by 1d4 for each spell slot level above 2.