Blight

Level 4 Necromancy (Druid, Sorcerer, Warlock, Wizard)
Casting Time: Action
Range: 30 feet
Components: V, S
Duration: Instantaneous

A creature that you can see within range makes a Constitution saving throw, taking 8d8 Necrotic damage on a failed save or half as much damage on a successful one. A Plant creature automatically fails the save.

Alternatively, target a nonmagical plant that isn't a creature, such as a tree or shrub. It doesn't make a save; it simply withers and dies.

Using a Higher-Level Spell Slot. The damage increases by 1d8 for each spell slot level above 4.