Assassins are way too good to MTW2, as are Spies really. Assassins because its much easier for a smart player to train them up and simply kill every AI general (command stars don't seem to grant them extra defense anymore), and Spies because three-four Spies is nearly 100% chance to open gates and because of the siege-wrecking bug AI Spies induce. I'm really suprised that with all the other buildings CA didn't think to include a Watchtower-Borderfort line again. Or at least made the Watchtowers you can build have some effect on Spies/Assassins.