As an action, you can throw this flask of turbid yellow liquid, hurling it at a creature, object, or surface within 25 feet of you . On impact, the vial detonates in a 5-foot radius. Any creature in that area must succeed on a Dexterity saving throw or take 1d6 fire damage and an additional 1d4 fire damage a the start of their turn for 4 rounds.  The area affected continues to burn for 4 rounds or until destroyed if flammable.  At the DM's discretion if the surface is flammable the fire may spread.