You will begin this mission on a plateau overlooking the ruins of the Autobot launch zone. Transform and boost down the track ahead, following the arrows as Metroplex wreaks havok in the distance. Follow your waypoints and be on the lookout for health pickups dotting the sides of the level. When you reach the bridge, several enemies will run out from your left and a few others will take up positions in the center of the bridge. Simply boos and run the enemies over, bashing them all into robotic bits. If you miss any, you can always fire off a few rounds with your primary weapon to mop them up. Speed past the bridge and go off of the jump ahead to reach the lower level.
Keep boosting and head up the ramp to the left to find more enemies. You can simply speed down the path to the left to run them all over and keep on boosting to reach the next area, but note that there is an ordinance pod to loot if you need some extra weapons. Keep following the onscreen arrows and your waypoint marker to blast past the last few enemies and into the Autubot base. You will reach a store, which you should access to upgrade your arsenal. Note that your ordinance doesn't carry over from one mission to the next, so if you had any consumables from the last mission that you didn't use, you will have to refill them now. Annoying, but necessary. When you are ready, loot the box in the upper left hand corner for some currency and then take the ramp across from it up to the second level. You will find an Energon Cube ahead, directly across from a massive Decepticon cannon that is shelling the Autobots. You will have to destroy the cannon, but first you will have to deal with a group of Leapers that swarm in below you. They will quickly lay waste to the group of Autobots below, so you may feel the urge to jump down and give them a hand.
In fact, it can be better to begin the assault from above, where you are less vulnerable. Fire upon the backs of the Leapers from far away until they notice and attack you, and then drop down to the lower level and enter the fray proper. There will be multiple weapons and health pickups scattered about this arena, so don't worry about wanting for ammo or health, as long as you can remember their locations in the heat of battle. The best strategy to use when battling multiple Leapers at once is to constantly be dashing in one direction. When both of the Leapers make their attacks, pause for a moment and choose one of the enemies to focus on. Take them out one at a time.
Unfortunately, when you have defeated the first two a third and fourth will enter the arena, not too pleased with the results of the last battle. They will quickly be aided by a third Leaper, who will fall into the arena shortly after its predecessors. Again, kep moving during this battle. Maintaining a state of constant movement is absolutely vital for survival here. Stay close to the corners so you can harvest the Energon Cube power ups as soon as they spawn and maximize your health. Just like the last battle, pick one Leaper and stick with it until it is dead, and then focus on the next, and then the next. This battle can be incredibly dangerous and harrowing, but it's also not the most challenging as long as you stay focused and maintain your wits. Fast reactions and good strategy are the differences between life and death when facing multiple Leapers. A good rocket launcher sure doesn't hurt the odds either; look for the flowing yellow silhouette of the weapon in the back right hand corner of the arena.
Once the battle is finished, you will be tasked with taking out the giant artillery cannon. Hit RB, point the reticule at the cannon, and hit A to make Metroplex take out the cannon. One down, and two to go. Exit the arena through the back left, grab the Audio Log from behind the stairs, and climb up the ramp to the next level. Proceed around the corner, over the catwalks, and around the next corner. Head to the left side of the area, past the box, and jump and boost over to the catwalks on the left to find a box with with more currency in it. Loot the cash and head back over to the main catwalk, and use the money you just earned to open up the Armory pod if you are so inclined. When you are done with the area, proceed past the Armory pod to the right and down the hall towards your next objective.