Fall of Cybertron was just released and it has one of the best implementation of Horde Mode out there in Escalation. In order to help you clear all 15 waves on each map, I dove head first into it to find a few tricks to help you out. There's More Than Meets the Eye to this game mode.
The very first thing you're going to want is a full team of four people. Unlike other Horde Mode variants in other games, you really can't solo a full 15 waves in Fall of Cybertron, even on Easy. Each map has four unique transformers, each one designed to fill a particular role in combat.
In order to beat all 15 waves, each person should use their abilities properly. Keep your medics protected, have your ammo supplier in a central location, and use your sentry and tank to help absorb damage. Escalation is really built around teamwork, like most Horde Modes are, and lone wolves are really going to have a tough time making it work.
The second thing to focus on is how you'll spend your credits. Each person starts with some credits - try to open up as much of the map as possible early on. It'll give you more room to move, should you get overwhelmed. You'll have to pay for health and ammo if you use the pick-ups on the maps, so again, make good use of your active abilities. Regening your health and ammo for free will let you save credits for opening more of the map, or buying the T.E.C.H. items.
You'll also see weapons scattered throughout the map. If you've played through the campaign you should be familiar enough with the weapons to know which ones you prefer, but generally the default weapon for each map is fine. The only one I really would recommend replacing is the Subsonic Repeater that you'll get on the Ancients map - it's not terribly strong or accurate and the high rate of fire will make you burn ammo fast.
Here are some things to keep in mind while fighting through the waves of enemies. You can actually melee through most of the cover, as long as you're pressed right up to it - use this little ability while you're reloading. Melee attacks are strong, and they don't delay your reloading timer either.
Make good use of the cover in the maps, making sure to switch your gun arm depending on which side the cover is on. Using your left arm can make the difference sometimes.
Make sure not to forget your vehicle form either. Not only can you move quicker, but also you actually take a little less damage in vehicle form. Plus Shockwave and Starscream are jets, which opens up the air for combat ideas.
As long as you go in with a four-person squad, play your appropriate role, and open the map up as quick as possible; take your time, be smart with health and ammo you should be fine, don't forget you've got three lives to work with. And put aside your ego early on - play on Easy to get acclimated to the way Escalation works.
Maps and the Factions you'll be playing as:
Oblivion: An interior map, looks like the interior of the Ark. You'll be playing as Decepticons. Megatron plays the role of tank with his Flak Shield, Shockwave is your medic with a Heal Beam, Soundwave helps out with a Battle Sentry, and Starscream provides your ammo with an Ultra-Power Core. You'll start with Scatter Blasters - a fine choice.
Ignition: This map takes place in the Gladiator arena that Megatron rose to power in. This map has some unique features, including an airstrike console and flame jets you can activate with credits. You'll be Autobots this time. Optimus Prime tanks for you with a Flak Shield, Ratchet is the medic (of course) with the Heal Beam, Bumblebee can replenish your ammo with the Ultra-Power Core and Warpath is your Battle Sentry man. You'll start with the Path Blaster, which is a solid choice all around.
Ancients: You've got a really small initial room, so open it quickly, or you'll be overrun. You're playing as Autobots here. Cliffjumper is the tank, for some reason, and has the Flak Shield, Perceptor is the medic and has the Heal Beam, Wheeljack has your Battle Sentry, and Jazz will fill your ammo up with the Ultra-Power Core. You start with the Subsonic Repeater here - I would recommend switching it out early on, but don't spend all your credits on that.
Downfall: Another small initial room, so open it quick. There are some defense systems you can turn on with credits on this map too. You're playing Decepticons here. Quake is your tank with the Flak Shield, Onslaught plays medic with the Heal Beam, Brawl helps tank with the Battle Sentry, and Swindle plays supplier with the Ultra-Power Core. You start with the Neutron Assault Rifle, which is a really good all around weapon, so focus more on map purchases.