As I've seen discussed before but never all together, here are some of the unofficial rules:

1. Only advertise your legion in your own legion thread or in threads looking for a legion. (the exception is if the advertisement is in your forum signature)
2. Only make 1 thread per legion.
3. You may 'bump' your own legion thread, though it is generally only acceptable if you are adding new information.
4. Satire of a legion is to have its own thread. If 'flaming' occurs the thread will probably be closed.
4. Wars may be declared in the threads of the legions involved, or may have its own thread. Note again that if flaming occurs the thread will probably be closed.