What do you think about the rules for HeroesPortal's offline tournaments?
http://heroesportal.net/land/rules.php?type=main
http://heroesportal.net/land/rules.php?type=off3
A detailed explanation of each prohibition:
http://heroesportal.net/tavern/?id=270698
I think this option is the most reasonable:
In Heroes III, the following is prohibited:
...
using any other (besides the allowed) glitches or bugs in the game. In case of any doubts, you should personally ask the Tournament Organizer for clarification.
But this point is quite slippery and controversial:
the following techniques are allowed:
...
Using glitches in the map editor, as well as implicit bugs in the game that occur without any player intervention.
(Василь Симоненко. Люди – прекрасні)