As your confrontation with Starscream begins, he will send in numerous footsodiers to fight you in his place. You will have a few seconds at the beginning of the encounter to skirt around the battlefield picking up weapons and ammo before the enemies start to flood in, so make good use of this time. You can find heavy weaponry to the left, right, and middle or the arena, making it easy to get your hands on some heavy ordinance. The most useful gun right now is probably your Riot Cannon, though, which you should still have equipped. This powerful gun can tear through many enemies with just one shot, especially if you took our advice earlier and upgraded it when you had the time.
Blast through the first wave of enemies using your Riot Cannon. This shouldn't be too hard; just remember to use the crates scattered all around the arena for cover, and be sure to keep a vigilant eye on your surroundings as enemies will come from many different angles and sides. After the first wave, you will have to face off against a small army of Shotgunners. This shouldn't be too much of a problem for you either, thanks to your trusty Riot Cannon. Pick them off with the explosively powerful weapon before they can close the distance. Also, try to be aware of your surroundings, which themselves can kill you during this phase of the battle. Flames will sometimes spew from the left and right sides of the battlefield whenre orange holes in the piping jut out. Note that these flames can kill your enemies, too, so if you are having a tough time dealing with all of the opposition or find yourself running low on ammo, these flames can be your best bet.
After this wave, the crates on the ground will meld with the floor and four large, central pillars will arise from the ground. This will be a sniping wave. You will see the insect-like form of the snipers rushing into the arena from directly front and center. See if you can pick one or two off before they can land. The rest of the snipers won't be very hard to kill, as they are very lightly armored and telegraph their attacks with their red lasers sights. Finish off the snipers, and then immediately refill on health and ammo if you need either. You will be facing off against two Leapers in this next wave, and they'll be significantly tougher than any of the enemies in the past waves. The key here is to stay nimble. Don't hesitate to use your dash ad naseum to avoid the jumping attacks of these powerful enemies. You can even use your hover ability to make yourself temporarily invulnerable to the Leapers and their vicious attacks. When the enemies pause, hit their backs hard with the Riot Cannon. You can even dive bomb right into the weak spots on their backs for massive damage if you are fast enough!
Don't let your victory go to your head, though. Three more Leapers will rush into the arena as soon as you defeat the first two. You may find yourself in need of more ammo now, so sticking to the walled-in corners that are less accesible by air, rush around until your guns and health are full. Never sit still, not even for a second. To do so in this difficult wave is tantamount to suicide. Try to keep all three of the Leapers in your line of sight at all times. This means leading all three of them to similar locations and then quickly skirting behind them. Focus your fire on only one at a time if possible; this can be a difficult tactic to maintain in the long run though, because all three enemies are constantly moving and jumping about and they all look the same to boot. If the battle ever becomes too overwhelming, use your hover ability to buy yourself some time and regenerate your shields up in the air. As soon as you hit the ground, be ready to start running and dashing again.
With a fully upgraded Riot Cannon, this battle is manageable but still tough. You will have to be very light on your feet to come out unscathed. Whenever you see a Leaper take to the air, immediately drop whatever it is that you were doing and dodge to the side to avoid it. With three powerful enemies flying around everywhere, you can't afford to take chances. When the first Leaper falls, the battle will become significantly easier. Chances are the other two will have suffered at least a little damage in the initial assault, so finish them off as fast as you can and approach Starscream.
Starscream will give you a load of his typical egomaniacal spiel. Hit X to blast him with the gun of your tank, injuring him and sending him running off with his tail between his legs. Ascend the throne where you belong and regain control of your disheveled and demoralized Decepticon army. With Megatron back in the lead, they will be reinvigorated for a new assault. As it happens, you will be the spearhead of that assault. Your troops will give you a status update, and Shockwave will lay out the plan. You'll be powering up the Energon tower and taking off for more habitable lands. With that, Megatron will board a dropship and take off for the battlefield.
His dropship will naturally be shot down, but he'll land unscathed, initiating the next mission.
