This cheat allows you to release all of the multiplayer wizards,
so that in battle mode there are 33 wizards to choose from!
When you first play the game, there are only 8 wizards availble.
As you successfully progress through the campaign
more wizards are released, totalling around 26.
More details here.
However, to release the remaining 7 wizards, you will require one of the following files.
Both produce the same effect.
Now when you enter the battle mode options screen,
clicking the arrow buttons underneath the portraits will cycle through all 33 wizards, now including:
Download this file to your pdata directory, overwriting any file that currently exists.
Open this this registry file to instantly change your settings.