2-2 is more of the same in the way of enemy compositions, which means more and more armoured units. You'll want the same types of echelons you use for 2-1, an AR echelon to hunt down the boss, and something with AP to hold down the starting heliport.

Awwwwww shit MC Ouroboros back on the mic for another cube chapter. This time with infinitely more annoying obstacles! Remember Arctic Warfare? Yeah. We got mechanics from that now. Jupiters, one ways, more annoying boss mechanics that actually require some micro, and more armoured units than you could ever want. You name it, we got it. 

Singularity is where this game starts turning from raifu collector into something that could be called a pretty nice strategy game. As such, prepping for this is pretty key if you're not already a strong player. 

Were you able to clear chapter 3 of Deep Dive? If so, congrats! You can actually clear cube+. 

Singularity is the first "modern" style event, and introduces branching chapter maps. This gives an overview so you can figure what is what.

DD's ranking map is, as always, unlocked by clearing out all the story maps. It's a 15 turn long map where you get points for meeting various objectives, and your highest scoring run is counted for ranking purposes.

Which classes are available in the game, and what you use them on with what buffs.

Since this comes up far too often and people apparently don't like doing complicated math like "aim for enemy evasion x3 as your accuracy stat" themselves, NUMBERWANG!

Last map, not as much of a clusterfuck as 2-4, thankfully. The only thing that's remotely difficult is Gaia, the boss of this chapter, but even then she's not too bad to fight.

This map is simpler and less of a huge hot mess than 3-2, hoo fucking rah.