Arknights WD-8 Trimmed and Auto Deploy friendly
The level boss for this one isn't difficult, just need to understand the mechanics.
What I did here was to wait for him to reach a certain part of the map before taking him down the first time, while making sure the rest of the minions did not get through.
As for his second form, I waited until he reach a point where my key operators are able to do one massive damage run and this includes operators slowing the level boss down to within one box.