I found out how to capture/destroy the HQ in UFO mode so you can't be killed by the enemy. I use this mainly to piss off the other so called "hackers" on the other team as they can't ever capture the HQ. This also works for capturing flags on Domination.
how then? i was able to do this in one game and after that i couldnt do it anymore all i did was go to the hq turn ufo mode off then turn it back on and i was still capturing