You must complete 2 tasks: 

1. In order to inflate the fire, players need to inflate coals through the bellows. If coal is not fully ignite, they will start to blow out. When the coals have been fired up completely they will start to beautifully glows.2. It is necessary to put the right ingredients in the cauldron. If the weight of the ingredients is correct the riddle is triggered. The operating weight can be changed. 

 When activated, the electromagnetic lock is turned off. 

 * This riddle is suitable for escaping a room of a witch or alchemist. You can use it in the modern kitchen, and change the cauldron to a pan. By changing the design it can be used even in a spaceship escape room. But then it should be a technical cube in which it will be necessary to put different electronic boards or cosmic crystals.