Umm well, let's say you've got a map with a lot of modes and this map is being played in a professional league.
The game is then hosted by a bot, because every team needs to be fair (otherwise there'd be a player as host which could choose all settings).
The bot will recognize that it is a league-game and change Warcraft's settings to change the handicap of all players.
Depending on the handicap the players have, the game mode will change.
So let's say it's a "Pro-league", then the game mode will be set to Insane / No revive" or something.
If it's a "Semi-professional leage" game, then the game mode could be set to "Normal / 2 revives".
These are just examples, but I hope you get the point xD
How to use it: no idea, I don't have the bot :/