I was going to suggest something about this, but I became too lazy.
My suggestion is that we should have it the way we did last time with the boss in the tower, but this time have both the flag and the bosses. Instead of having the boss up in the tower where there's barely any room, have it outside the castle in the open where everyone can see and attack along with the flag still up for grabs to get points.
So in order to win the game, one of the teams would have to kill the boss first, or if no one can defeat the boss, the team with the most points, by gathering flags within the 15-20 minutes or however much time it is, win. The amount of tickets would vary on how the team won and the amount of flags gathered.
So if your team defeated the boss, that would an automatic 15 or 20 tickets (or whatever you prefer is the best amount), along with the amount of flags gathered which gives 1 or 2 tickets per point (flag(s))? This way, if they want to win fast tickets they would use most of their team to defeat the boss along with getting some flags if possible. Or if they can't defeat the boss they have another option of collecting many flags as possible until time runs out. And also if both teams can't defeat the boss, the team with the most flags win the game, but the team that won would receive a bonus of maybe 5 or 10 extra tickets.