Cloak of Karsus

This is actually a 10th level spell. Consult you DM on how and when you can learn this.

You exhale deathly smoke from your nose and mouth, which coalesces into a huge cloak of decay that wraps around you, killing everything in your path. The cloak is a 15-foot-radius, 5-foot-high cylinder that moves with you. Creatures that start their turn within that area or that move there for the first time in their turn must make a Constitution saving throw, taking 30d10 necrotic damage on a failed save, or half as much on a successful one. A creature that is reduced to 0 hit points by this spell is liquified, dying instantly and having their corpse destroyed.