I play VolSent on Platinum. (And topscore.... sometimes)
That'll be down to you watching the other players reloading and locking them up with Shield Boost, right?

Joking, of course, but it did happen to me twice in our Volus game - remember when I was dead in the EZ? 2.5k hours of MP gameplay and I was so panicked I was trying to take cover with a Volus! 
OT: I'll always leave a preset Giant lobby, but I don't mind playing there. It's Tuchanka, after all. Extraction wave always amuses me, because I don't care who you are or what you are - I won't be with you in the EZ until the final seconds, and I don't care if you die and get stomped because you've run out of all the missiles you failed to fire during the waves that mattered. Same with Reactor - I'm chilling on the opposite side of the map until the 30 second mark.