To enable "Test" keys you must: go to
Disciples III\System\ folder located in
My Documents\My Games\Disciples III\System\
there you need to find the "user.ini" and open it.
After that just add this line: int bGameplayTestKeys = 1

Now in game you can use Test keys like:
[F3] - Add resouces
[F6] - Auto gameplay (like auto battle)
[F7] - God Mode