You exhale a cloud of poison that magically expands to fill a 30 foot cone. Creatures in that area must make a Constitution saving throw. On a failure, they take 4d12 poison damage and become poisoned until the start of their next turn. On a success, the target takes half as much damage and is not poisoned.
The area is lightly obscured until the start of your turn, and any creature that ends their turn within the area takes 2d4 poison damage.