I'm a leader

The way I do is a lotto. Players who were the most active in the current war (our server's war usually consist of a total of 4 battles across both days) are put into a raffle. Players who have won a legendary box before can't win again unless there is nobody in the raffle who hasn't gotten one. Then I just proceed to raffle out the boxes. If a player didn't get a box, the next time they are in the raffle they get an extra entry.