Urban Noir Fantasy World

You inscribe a rune of toxic energy on a solid surface within range, which stays dormant until triggered. When a creature moves within 5 feet of the rune, it explodes in a cloud of poisonous gas. The creature must make a Constitution saving throw. On a failed save, the creature takes 5d8 poison damage and becomes poisoned for 1 minute. On a successful save, the creature takes half damage and is not poisoned. The rune lasts for up to 10 minutes or until triggered.