HP Dueling is a multiplayer combat game where players duke it out in Harry Potter Wizarding Battle style literally anywhere in SL! The more players you successfully jinx, the more experience points you earn, allowing you to level up and learn more powerful spells and use better wands!
Or play The Battle of Hogwarts on the Hocus Pocus land. This game, based on World of Warcraft's Warsong Gulch, allows you to team up and fight for control of the Wizarding School!
Just search for 'hocus pocus' in Find --> Places and apparate here!