Oh look, it's our old friend Doomed Wall from the second article. Last time we didn't get to use it because of Shiver Yeti, but this time there's no freeze. Notice anything else here that might counter Doomed Wall? Think carefully. Very carefully.
Okay, trick question, there's nothing that counters Doomed Wall here. We've got 4 HP absorb.
A very slow unit but a very powerful one, Zemora tends to dominate any set with more defense than attack. The gamepedia article (written partly by me) tells you most of what you need to know: get it soon if you plan on getting it at all.
Another key unit, Amporilla is also at its best in otherwise defensive sets. It is susceptible to burst damage and counteraggression but will easily win the game if the opponent fails to pressure you.
Probably the best alternate econ unit in the game. Doomed Drone is ridiculously efficient when you get full value from it (it defends on its last turn). I like having this unit in my games because it mitigates player advantage by providing more diverse build options to both players.
Key unit #3 - we've got one of each color now. Odin requires a large economy, but is an extremely efficient purchase. Note that clicking Odin is usually bad barring one of two circumstances: either no damage is incoming so it's not getting absorb if you defend with it, or the opponent is very susceptible to sudden pressure.
Grenade Mech mostly serves two roles: a pressure unit to make your opponent crumble when they're already struggling to defend, or to be bought directly after a high-tech blue legendary like Odin or Defense Grid to get rid of some of the Blastforges that you don't want anymore through it's click ability. You don't start with Grenade Mechs (unless your opponent goes low econ red rush), because they aren't mathematically efficient - they're only good purchases in the late game because inflation has risen and Grenade Mech scales up sharply with it. It's a support unit.
Last unit. Another slow but powerful legendary like Zemora, has a higher buyrate but a lower impact on each set it's in. If you ask me, the default should be to buy this unit when it's in the set, especially when you have strong defense like Doomed Wall.
Okay, so we've got 4 key units: Zemora, Odin, Gauss Fab, and Amporilla. Zemora and Gauss Fab are weak versus Amporilla (because they're too slow and don't put on enough pressure), Amporilla is weak versus Odin and Grenade Mech (because they can suddenly threaten a lot of damage and red has bad defence), and Odin/Grenade Mech is weak versus Zemora and Gauss Fabricator because a player with access to Doomed Wall absorb and lots of green for Forcefields will be able to hold off the pressure plays that the blue units facilitate while Zemora/Fab finishes building and wins the game. So it's a rock-paper-scissors set. This kind of set is by far the most interesting because there isn't just one strategy that is optimal; you have to play reactively and try to be the last one to commit to a strategy so that you can counter whatever your opponent does. My advice for playing this set: take your time and think carefully on the early turns, ask yourself every turn if your opponent has committed to a strategy. If so, go immediately for the thing that counters it. Before you pass your turn, ask yourself if you're committing to a strategy that your opponent could still counter. If so, go back and rethink your turn. Buying an early Conduit is probably losing because the opponent can just go Amporilla and both of the units you can buy with your green don't really help you against that. Buying an early Animus is also fatal because the opponent can just beeline to Odin and then spam Grenade Mechs while constantly clicking both and force a breach. A third Engineer on turn 2 is probably safe because if the opponent goes Zemora you can quickly get an Animus and still go Amporilla. You won't have to float too much energy because there's Doomed Drone.