After purchasing a few things at the store, head to the left and around the corner towards the flaming hall. Hit X to kick the debris out of the way and form a path ahead. Climb down the ramp towards the second Decepticon Warp Artillery Cannon. When you emerge outside, you will find yourself at a crash site littered with Decepticons. You will have the height advantage, and ordering an artillery strike from Metroplex is a simple matter of hitting RB and then A. Kill them all off with the artillery, wiping up whoever remains with your primary weapon. When they are all done for, jump down from your perch, refill your ammo from the cache by the downed ship, and head towards the stairs at the back right of the area. More enemies will await you atop these stairs. When you reach the top, blast the enemy on the left and then the enemy on the right before dashing to the right to find some ammo for your secondary, heavy weapon. With the area mostly cleared out, head back outside and to the back left side of the arena, where you will find a short set of stairs leading up to a slightly elevated platform with a few fellow Autobots defending it.
When you approach your waypoint marker, Warpath will fill you in on the situation. It's chaos on the battlefield, and they need the help of Metroplex to survive. Pick up the Diffraction Barrier shield if you didn't buy one earlier; otherwise, save it for later, as you may just need both in the intense battle to come. Decepticons will begin filing into the arena, first from directly across from your position at the back of the arena. Zoom in to your weapon's sights to take out these enemies from afar as they approach. A Marauder cannon will be marked with a red icon soon. It will be heading towards your position from the left. Point Metroplex at it and destroy it. You will also need to defend your left flank from flanking enemies, so set up the Diffraction Barrier item in the entryway to the left and stay behind it, using it as cover as you pop out and blast the approaching Decepticons. Note that grenades can still go through the barrier, so you may need to mount a tactical retreat if one manages to slip through your defenses.
After defending your left flank, don't grow complacent. You will have to fend off still more enemies coming from the center and the right of the area. Don't waste any time in getting over there and setting up a second Diffraction Barrier if you have one; use the cover in the central arena effectively if you don't have a second of the shields. Note that you can grab ammo refills from behind the central barrier in the middle of the courtyard that you occupy if things start getting hairy. Shotgun soldiers will quickly hone in on your position; now might be a good time to use the Energon Cube behind the cylindrical barrier in the courtyard. Grab it and hold off the Shotgun soldiers with everything you've got. If they get too close to you, you are as good as dead.
Following that close-quarters attack, you will have more enemies in the courtyard outside of your little arena to deal with. Pick them off at long range if possible. If not, try using Metroplex's artillery strike ability to take them out without having to leave the safety of the central arena. You will find the last remaining enemies, a group of rocket soldiers, atop a long staircase on the opposite side of the area. Coincidentally, that's just where your next objective will be. Head over there and wipe out the few remaining enemies in this temple, and then follow Warpath to the large statue head blocking your path. Hit X to help Warpath remove the statue head from your path. Grab the ammo from behind it and then proceed down the hall towards your next objective.
