A friend and I struggled with this one for a while, but we now have the technique pretty much down. I'll list a few basics:
1. One engineering chassis and one assault chassis is our reccomended loadout, we used a Selker and a Karlsson.
2. Weapons wise, Selker should be packing shotguns for quick kills, or a grenade launcher also seems to work. On the Karlsson, I used 3 "The Scythe" machine guns, a "fighting wolverine" sniper and a Brenneke's Revenge shotgun underneath that.
3. Tactics wise, first thing to do is get positioned. We had the Karlsson on the left hand side dealing with threats mainly from the left hand pathway and the Selker using it's speed to cover the right and the centre. Obviously the Karlsson can reinforce the Selker with added firepower where needed.
4. Turret placement is the real key here. Firstly, you'll want machine gun turrets up on both sides of the base as soon as possible to help deal with the Aerial waves. Aerials do a ton of damage to the base, so keeping them controlled is top priority. Get machine gun turrets down and upgraded to level 2 with one or two 3's before aything else.
5. Dampening generators are a life saver. They're cheap and they spread the waves out brilliantly, letting you deal with one set of enemies without another sneaking in cheeky hits on the base. We found the best place for them was a small perimeter just out side the base, ad then one on the centre pathway about halfway down, and one on the right hand side pathway. If you have spare scrap after dropping your slowing turrets and machine guns, minefields never hurt anyone.
6. One final but important tip, the largest group of Aerials always comes from the left hand pathway, so make sure whoever is guarding the left in the Karlsson thins them out as much as possible before they even reach your turrets, otherwise your base is going to take some hits.
Hope this helps a little.
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