Death by 1000 Farts

When you cast this spell, a creature within 5ft is instantly hit with the smell of rotting anus and must make a constitution saving throw. On a failed saving throw, they immediately take 3d6 necrotic damage. On a successful saving throw, they immediately take half damage.

At Higher Levels.  At lvl 4, the caster may spray in a 10ft cone (4 squares total, 1 in front, 3 after that).  Whether cast as a 10 ft cone or not, the spell adds adds 1d6 and, if a creature remains inside the area of affect, they take an additional 1d6 necrotic damage at the start of their next turn.  At the start of the turn, the creature must make a successful constitution saving throw to end the effect.  On a successful roll, the effect ends and they do not take additional damage on their next turn.

At lvl 9, the caster gains the ability to fart snipe to shoot a cloud of 15 sq. ft (3x3 square grid) with the center being a target and shoot it up to 60 ft.  The spell also adds 1d6+7 to the damage roll.