Duplicated Brothers:
     This cheat only works in the Lotus campaign. Do the following:

1. Build a Crypt of Brothers as soon as possible. 
2. Build three Watchtowers and summon three Brothers. 
3. Put the Brothers in the Watchtowers. 
4. Destroy the Crypt of Brothers using CTRL+D. 
5. Build another Crypt of Brothers 
6. Summon the three brothers again. Now you have six Brothers. 

Easy Yin Points for Serpent and Lotus Clans:
     In  the  Serpent  Clan, use Ronins and equip them with Yin Blade.
Then, force attack them to trees while using Yin Blade.

     In  the Lotus Clan, summon the 2 Brothers Lythis and Tausil, then
have  them attack water (force attack them into a very shallow spot in
the  water  or  other  similar  place  and also a little deeper on the
water). While they attack, you continuously yield Yin Points.

Fast Total Destruction:
     (This  cheat  is  only for an un-updated version of Battle Realms
which  means  unpatched.)  This  is quite easy, all you gotta do is to
find  an  opponent's  building  and press ctrl+D. This cheat will work
when you see the building collapse immediately.