The AI's ability to drop an enemy unit anywhere in your base, and without any warnings at all, really disrupts the flow of the game. It can be completely crippling if you can't destroy the unit fast enough before it gets repaired. Unless you're looking at your base, it's find to even know you're under attack. Having your base completely destroyed because of one enemy unit that your own units won't attack can ruin the current game. The ability to turn this off would be great.