I'll try and clarify my earlier response. I have Versailles there is no AOE on the health bonus, it is like library research and applies directly to all troops you have, both attack and defense. I guess you could call it an unlimited AOE. The AOE only applies to the slow down effect which is literally one square past each side of the building just like any other caltrop. Again it is more useful for an active attacker as the heal amount you receive from your supply carts goes up as well, this is do to the percentage of heal being based on your total health. Really useful on cavalry. Angkor is easier to defeat as the defenders are stuck on AI, just rally your troops together outside of angkor's range if their is a general and the dumb general will follow your troops out and die quick. The rest of the troops die almost as easy as if you didn't have Angkor. If you have a bad defence Angkor will help, but this game is about attacking more than defending and Versailles covers both.