I am having troubles with annihilation mode. The main problems is that I dont know what units are the best to bring down an enemy HQ. I know that you first have to win the match but even having a land raider and obliterating your enemy you can still be in the situation where you troops arent antibuilding effective.
I know that two squads of stormtroopers with meltas will tear apart an HQ building in not much time, also wraithguards are extremely effective but... What else? What about the other races? Plasma cannon (SM CSM) are effective but only one unit in the squad has one and you cant build 2-3 because you are near the pop cap.