Events happens in various days and are unlocked at Player level 4. They have Friendly rules but all other rules can change per event! You can find out more about Friendly Rules here

Upon reaching certain amount of victories, you can get intermediate rewards (Gold, Gems, Clones, Eggs) and the final reward; the Event Egg that will contain more rewards! Sometimes there can be a an event where you can unlock and win brand new Clones!

If you lose too many times, the event ends but you can get extra attempts using gems. Extra attempts are free for all the Brawl Pass owners.