Vial of stench is a nonconsumable potion which is made by using a bowl of chopped onion with an unfinished irit potion. It is first created during the A Guild of Our Own caper and can be made afterwards. It is unusable unless enchanted, as the stench would affect the player as well as the victims. Chief Thief Robin in the Thieves’ Guild casts a spell on it to activate it into a vial of stench (a), which can be used. If the potion is lost, players have to make another Vial of Stench and have it enchanted by Robin.
After A Guild of Our Own players must have it re-enchanted, and can then use the activated potion to sell stolen merchandise back to the stall owners immediately after the theft. This is helpful when attempting the Ardougne Tasks. To use the Vial of Stench, simply keep it in your inventory while stealing from the stalls.