I'm looking for three people that would be interested in trying to earn the Bros to the Close achievement. Message me if interested. Looking for NOW, however, if no one is available, I'll be shooting for around 7pm EST tomorrow (Monday the 9th).
Scratch that...that was quick lol. Thanks to the two people that jumped in, it was a cake walk. Mods can remove this post, or if it remains up, anyone else feel free to use it to try and find a few partners to go after this achievement with.
I did this myself and I actually found it a lot easier than I thought it would be. The trick is to give at least one marine a Lightrifle and make sure you stay ahead of every marine. Also, when you get to the four marines at the bottom of the hill, run in
front and shoot all the crawlers in the head and move forward. If you get on the turrets at the top of the other hill in front when you need to defend the LZ, it's so easy to kill the Knights.
I hope that helps! I tried this on my first attempt and it worked very well.
Also if you're attempting this co op, there should be at least 2 binary rifle pick ups in the section before you get to the marines. Make sure you have at least one bullet left and pass them off to the marines.