Team Challenges

Team Challenges are unlocked at x20 Stars (x30 Stars before the update 7.6, which added the Global Challenges and Combine Tokens) and are some "tasks" which can be completed to help the team. After the team has got enough points, a special reward is given to the players: Change Tokens, which can change Ad Events.

Types of Team Challenges
There are several kinds of challenges to do to get points which are the next:

Strategy

 * Prestige tasks are most efficiently completed with the Faster Barrels Ad Event so the player can obtain their first Barrel, prestige quickly, and repeat or by just restarting with Auto Merger or no ad event.
 * Fragment tasks are most efficiently completed with the Faster Barrels Ad Event. The player taps repeatedly over where the "yes" button appears for converting Barrels. If the player has removed his convert dialog, he can spam convert every spot he likes to and can complete it very fast.
 * Activate Ad Events tasks are most efficiently completed by choosing short Ad Events or starting them, force closing the game, and repeating.
 * Merge tasks are most efficiently completed by quick merging with the Faster Barrels Ad Event.
 * Collect Beams Just get Steel Beam storms or for the 50p challenge, collect 10 falling beams which are the amount of beams falling in a Faster Barrels / Auto Merge.
 * Collect Mega Magnets tasks are most efficiently completed by merging quickly with the Faster Barrels Ad Event.
 * Collect Magnets in Storms tasks are most efficiently completed by repeatedly using the Crazy Storm Ad Event or grinding storms.
 * Upgrade Star Pieces tasks are best completed by players who have saved up enough Magnets, Star Fragments, and Golden Scrap to upgrade enough all at once; if a player doesn't have those resources ready, they should let someone else who does complete the task to get rid of them-

Rewards
Once the team has collectively reached certain point thresholds, Change Tokens are awarded to players after the challenge season ends (5 days):

Team's Leaderboard
Here, the points of each member can be seen. It's useful for kicking and promoting too if you have any requirement for Challenge Points.

Trivia

 * This was the only way to earn Change Tokens until Quests were added (update 10.0).