Because I seem to answer this question constantly despite the sources on them, a quick guide to completing the kill based weeklies:

Before we get into the details of how calibration and enhancement works, let's first get around to how to unlock them. Both functions are accessed from the research menu, which you unlock at Commander Level 12. After that, you need to complete World 1-4 Night for Enhancement, and 2-4 Night for Calibration. Unlocking those is done by completing the story and subsequent emergency chapters,

Because shotguns were implemented and people kept asking how armour and such worked. Also because night battles have been a thing.

There seems to be a bit of a lack of understanding from newer commanders about what night battles are. Some may even think it’s this scary thing that’s fairly hard. Truth is, they’re very simple.

There are a few small changes between day and night battles. You have no command center, so you don’t need to worry about that being taken and you also have a limit on how many echelons you can deploy at a time.

And this is formations 101, or "How not to get your t-dolls slaughtered for showing up in a terrible formation." This will cover the absolute basics, with more detailed lessons such as compositions to come later. Most of this information is based largely on Korean server meta and information.

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.