Easy Persona Points
Near to the end of a battle destroy as much as you want but leave one building standing. Then save your game and destroy the building. and you will be victorious. After that, everytime you load that file you can simply destroy that one building. However, you will still receive the persona points when you win.

More Powerful Units
To make a Troll more powerful, have it pick up a tree as a club. It is slower, but much more powerful. To make an Ent more powerful, have it pull boulders out of buildings or rock piles to throw at your enemies.