What is the fine-grained topic of the following text: Collaboration beers are pretty exciting especially when it involves my favourite UK brewery Magic Rock and stalwarts of the craft brewery scene BrewDog and Stone Brewing Co. Magic Stone Dog is a saison pale ale hybrid beer by three of the best and biggest breweries in the world. Only return the topic.
Collaboration beer production by Magic Rock, BrewDog and Stone Brewing Co.