make your way down to to the right side, there's a small little barrier that basically very little can hit you from there. Tanks and Barrier champs will cut you in half. Don't be fooled by the bigger barrier, it's basically swiss cheese, you want to huddle behind the little one making sure nothing has line of sight on you. Basically head down there and clear the initial wave, you shouldn't need a lot of banner shield usage if at all. Take out the snipers on both sides ASAP they'll ruin your day. Once you spawn the tanks, drop a well, and rotate banner shields between 2 titans. You MAY have stopped generating orbs if you happened to step into the well while in banner shield, you need to make sure you're not in there. Tanks are priority, like, ignore the hell out of everything else and drop them as fast as you can. Once you kill the 2 tanks the rest of the enemies will then go chill out towards the exit, take them out from a distance and you're done the vehicle bay.