This game is dependant mostly on microing your units to beat your opponents in the arena. The host choses statistics for each round (supply limit, heroes, lvl of heroes, air allowed) and everyone prepares the best army they can create using every race. As many games as you want can be played, and each game consists of a few rounds. Rounds are done tournament style... 2 people at a time are randomly chosen to fight one another. Once everyone has had a chance to fight, the winners go on to the next round. This continues until there is a final winner. At that point, a new game starts with new armies and settings. Since battles are done 2 people at a time, the others watch these battles, for there is only 1 arena. This game can be played with any amount of people over 2.
Micro Arena v3j 189kb
To save, right-click on the above link, and choose "Save As". Browse to your maps directory and save there (usually C:\Program Files\Warcraft III\Maps\Download).