Season 1, Chapter 12, Mission 2 is the most important single mission in MAA. With two roulettes in two battles - including an epic roulette - it is easily the most efficient place to farm CP. Once you get there you will run it frequently and repeatedly, so tips on how to run it well are essential. The faster you can run it, the more CP you can farm. This blog will focus the main fight, with all 9 enemies, since the Viper epic is much shorter and less difficult to dissect. For my part, I have gotten to the point that I can often run the main mission, with all 9 enemies, in three rounds or less.
I use Bruiser WWII Cap with his personal (Fervent) EISO. Since WWII Cap and I go way back, I still have him ISO'd with all chaotics. For AISOs, Powerful on L1, L2, and L6, and L9 doesn't matter (Gracious if you feel you need it).
The third slot can be anybody, but if you're looking for maximum efficiency Union Jack runs it best of all.
In wave 1, it is Cap's job to hit the scrapper and build stacks of rage while countering everything. It is the agent's job to KO Moonstone (she can cause Cap problems). It is the third character's job to use Gene Inoculation on Cap, which will keep him free of bleed, stun, and The Baron's Mark. The Gene Inoculation is essential, as any of those debuffs can and will derail the flow of the fight.
In wave 2, it is Cap's job to maintain 2 stacks of Enraged and continue hurting everyone. It is the agent's job to hit Bowman and gain CQC. It is the third character's job to not screw it up.
In wave 3, Cap will probably need to refresh Shield Guard. The agent needs to single-target attack Hammer, with CQC follow-up. Third character can do any other mop-up duty necessary.
Shield Guard is the key to the run, because it maximizes the number of actions your team can take. In the standard sequencing your team will take three turns per round; the enemy team will take 5 or 6 turns per round, depending on which wave. If you can take one extra action on each of your opponent's turns you can very nearly triple your team's number of actions. If you're double-countering with the Fervent EISO, plus follow-up countering and precountering with Union Jack, you'll easily double that again. When you compound these free actions with increased accuracy and damaged from enraged, you're looking at a significant increase in damage output over standard sequencing. The best part: these are all free actions! You don't even have to click to make them happen, you just sit back and watch it go.
To that end, everything you can do to make Shield Guard happen is to your benefit, and that definitely means using the WWII alt, since that has the most Shield Guard of all. Some players prefer the tactician flavor because of enemy blasters, and I can understand that on paper but I disagree with it in practice. The bruiser can easily run the fight with two stacks of enraged the whole time (which means much more damage than one extra offensive action each round), and the rest of the team can KO those two enemies. Using the bruiser pajamas also means that the second fight against Viper runs more smoothly and completely devoid of Combat Reflexes. Be aware: there is a certain faiulre rate in using the bruiser suit, when Moonstone can go first and KO Cap before you get a turn. This happens to me maybe as much as 1 in every 50 fights (probably less, it's quite rare, I just haven't tracked how often it happens); this really is no big deal, since the only thing you lose by starting over is 10 energy, and 10 energy is very easily replaced.
The one time you wouldn't want to use the WWII alt is if the third character is also a protector (such as Groot or Thing). In that event, the Captain Steve Rogers alt is the best choice, so that the two characters' functionalities do not interfere with each other.
The agent's primary job is to kill blasters. The two blasters in this fight are Moonstone and Hammer
The most effective means I have found of eliminating Moonstone is Goblin Glider, especially if you can make it crit. Please note that Goblin Glider is not limited edition, and is found both from the 1.7.3 epic boss and on the daily roulette. In my opinion, this is the best non-LE weapon in the game: it attacks stealthily, it hits hard, it hits harder against Flying targets, and it hits even harder when it crits. I normally remove Moonstone with one shot by using Neurotrope followed by Goblin Glider. If you cannot seem to get the Glider to drop, my second choice for this slot is Transcranial Stimulator, or TCS. Now, TCS does not hit nearly as hard, but it is psychic and is highly usable in other phases of the game as well. It is available in the store for the bargain-basement price of 32 gold (I will brook no complaints about the gold price. I paid 64 gold for mine, and another 48 to reforge it. If you can't find a way to acquire a weapon that I consider to be worth 112 gold, then you and I have nothing left to discuss). If you are using TCS you may want to augment the first round with extra damage, such as from Golden Heavy Ion Beam or some other QA attack or effect.
Now, you're probably wondering why I recommend using a scrapper agent for killing blasters. Tactician agent would be the obvious answer, would it not? Obvious, yes, but not more effective (again, in part because you don't have to change clothes before taking on Viper). And the reason for the scrapper emerges in wave two. You'll want CQC for attacking Hammer in the third wave, so in the second you should attack Bowman. Since he hides behind two protectors, you will want something stealthy (Goblin Glider) or Psychic (TCS) to get to him. If Militant has not put up his Hail Hydra protect, you can instead use the AoE attack to hit Bowman and gain CQC if you prefer. Once you reach wave three, unload your agent's biggest single-target attack onto Hammer and follow-up on him. He might - MIGHT - get one shot in on Cap, but you'll make him a corpse long before he does it a second time. Once Hammer has entered the next phase of the circle of life, clean up whatever's left. Your Goblin Glider or TCS will allow you to hack away at your leisure at Zemo and Tactical Force, and there's little they'll be able to do about it, if Cap and the third character haven't already buried them.
The agent's secondary job is to stay out of the way of Cap.
I leave this vague because I often use 1.12.2 for leveling my new acquisitions (the xp sequencing works remarkably well early on: the Viper battle to get to level 2, the Zemo battle to get to level 3, Viper + Zemo to level 4, Viper-Zemo-Viper to level 5, Zemo-Viper-Zemo-Viper to level 6). As such, I have used nearly every character in the game in this third spot, and the only ones who force a change in strategy are the aforementioned protectors.
However, if you're running the level just for CP and not for xp, here are some good options:
Union Jack - easily the best Cap team-up. Follow-ups to counterattacks and preemptive shots really speed the fight along.
Rocket Raccoon - if UJ's follow-ups are as fun as a barrel of monkeys, watching Rocket blast away AoEs time and again is an entire wildlife preserve full of primates. Murdered you, indeed.
Black Widow - when all else fails, Flying Kick. Especially in her tac grey alt.
The following characters are not ideal:
Peast - you'll never quit bleeding. Just put him in his base form if you need to run with Dr. McCoy.
Chase Stein - his greatest asset is his greatest weakness. You want your enemies taking more actions, not fewer.