For ch 4, I actually ended up grinding hard enough to get my echelon in a good enough shape to deal with it back before I made the ch 3 post. The only real difference is one more level on skorpion to get her to four link and the addition of 16lab AP ammo. Thankfully I didn't need to level my second echelon at all to do their assigned job of "DEFEND HELIPAD". 

(Skip to strategy if you don't want to hear the updates going into ch 3) 

(As always, skip to the strategy section if you don't wanna see this.)

(If you'd like to skip past all of the reasoning for my echelon setups and stuff, go down to the video/strategy section)

So, since Korea currently has the upcoming event for global, I decided to make a new account to test it out. The goal being to give a good idea of what kind of power you actually need to take down the event. So far I've been working on two echelons for this, since it seems like its highly recommended to take two.

First echelon: 

The way construction works is by giving various doll and equip classes resource thresholds, within these thresholds, anything can drop.

The game's accuracy formula is surprisingly simple.

Repair times: