They serve as the usual roaming characters that must be collected by tapping. They spawn in groups at various times (after each group has been tapped).
The Magic Brooms are characters from Walt Disney's film Fantasia. They are the primary antagonists in "The Sorcerer's Apprentice" segment.
They have become famous since their release and have been cast in many Disney related productions and events. Despite their antagonistic roles in the film, this does not carry over to later appearances and are seen to be good friends with Mickey Mouse.