Why is Trial of lavor Start in your alliance?

So Trial of Lavor starts in Alliances. Anthill 12+ is required to battle in trial of valor. But can you tell me why does it start in your alliance?
Screenshot 2024-09-06 145427
This is also an alliance event.

hello
Yes, this is a weekly event. which is done in three consecutive days. To get more damage points and get rewards, you attack it with your best power for 15 times every day. The total of 5 damage on each day will be the score of that day. For the first day, the recommendation will be the guard , the second day Shooter and the third day carrier .