What are the rules that are applied for deciding when they are going to use them? I can't seem to make them throw any at all. Admittedly, I haven't played the campaign yet, just testing how it plays via New Battle, maybe in campaign it would be different. But in New Battle mode the aliens don't seem to throw grenades under any circumstances. I repeatedly specifically grouped several my guys within a copule tiles of each other to provoke a grenade throw, and nothing.