They should make it just on auto => rewards for all participants (like in One piece game). Less problem for the leader and fair for all players.

Why do some people act like every p2w players buy hundreds of scrolls etc ? Only a few do that. Most people who pay for this game most likely will buy jonin medal, gaara and eventually a few $ when there is some interesting event. Scrolls for participants won't ruin the game. If there are just 2 strong guilds, just merge servers and fighting will be more challenging.