One of the building that will be available to players once we arrived in FarmVille’s Haunted Hollow is the Monster Lab. It’s a breeding building where we place up to 20 Monsters inside the Monster Lab. Once you harvest the Monster Lab it will give “Serum” on which you can use to create more Monster by exchanging these serums. The more monster the Monster Lab has the more chances it gives rare color “Serums”. You can have multiple built Monster lab. All exchange Monster can be found in the Gift Box.