When you are in a Fortress you will need to team up with four other players. To get started one player needs to consume a Runestone, which makes the lobby where other players can join the team.
Other players can join the lobby until five total players are in the lobby or the timer runs out. If another player tries to join after this they will enter into a new lobby. Here are some tips to win more challenges.
Play with friends. In addition to unlocking a larger reward, you can divide and conquer your Foes.
Attacking consumes your Spell Energy so be sure to visit Inns to replenish your Spell Energy before entering a Chamber.
Join a Wizarding Challenges with some Potions in your Vault. Potions can be used to replenish your Stamina and increase your chance of success in combat.
Your Profession influences your combat proficiency in Wizarding Challenges. Each one has an affinity advantage against certain Foes, as well as an affinity disadvantage against other Foes. For example, Professors deal additional damage to Curiosities, like Pixies, but sustain more damage when battling against Dark Forces, like Death Eaters. Unite with other wizards and witches and form diverse teams to take advantage of these affinities.
Use Strategic Spells to help your Teammates and increase your chances of winning.
You can find teammates in real life as you walk around or look for player groups.