1. Standard approach.
The tournament organizer prepares the tasks.
2. A non-standard and more interesting approach.
We have many good players. Moreover, they play in tournaments, so they definitely have some saves, for example, before key battles.
Therefore, we can, let's say, pool our resources and have three tasks for conducting battles, and they will be from different people.
I think this is more interesting.
And then, for each item in the competition - for example, the fastest completion of the game, taking into account the amount of mercury collected, or taking into account the number of skills acquired, etc. (capturing a hero, preventing them from escaping, etc.).

Орден Феникса – харизматический :) лидер