Im surprised that he isnt reviewed yet.

• He is an expensive 5-ER card that is restricted to minion/side sch
• Can flex a sum of 6x between THW and ATK over two turns, plus a chump block (not worth imo)
• Can flex a sum of 9x between THW and ATK over three turns (last 3x instance is unrestricted). Decent for his cost imo.
• Maria Hill (Hero) + Field Agent or Med Team can make him stay longer. Though he is a direct competitor of Dum Dum Dugan, I think both can coexist for a great overall table pressence
• In minor effects, we have him as AERIAL trait for tribal decks and for Eyes in the Sky
• Other minor effect if that he brings the exclusive EXCALIBUR trait for multiplayer Strength in Diversity plays
• In a very unreal, voltron-gunboat deck, we can have him Honorary X-Men + Mission Training to add 4x to the sum of Gunboat Diplomacy
• In a multi-aspect hero (Warlock, Spider-Woman), can be affected by or combined with: Flying Formation, Aero, Cloud 9, Air Supremacy, Bombs Away, Aerial Intervention and Wingman

• Already mentioned (by @alatreon): Ms Marvel's (Hero) "recur" feature plus her Biokinetic Polymer Suit + Shrink; increases its maximum THW by 2x3 (+6, a total of 12 THW)

• Jubilee (Hero), where Three Steps Ahead was first released, not only have a suited kit for mix, but her Jubilee's Coat adds an extra instance of 3 THW (A total of 9 THW) for a scheme that you choose (can even be a different, 4th scheme)

• Other cards can combine with said characters' kit and increase the instances by 1x3 (+3 at its maximum): Operative Skill, Passion for Justice (by @waltercardcollector)

While its cost is expensive and you have to build around the card in order to maximize its effects, the built-in ability to distribute three instances of 2 THW gives a flexibility that very other few cards have (All-Points Bulletin, Gunboat Diplomacy). In resume, this card will dominate as central key of decks that will become based around using it.

This card is very good for any hero that cares about attaching upgrades to minions. It enables a whole ton of synergies in the Aggression aspect alone, potentially more if you manage some kind of cross-aspect deck (for example with Spider-Woman, or playing certain campaigns). Cyclops also has great synergy with it.

One of the best things about Air Cover is that it looks for the card in both the deck and discard, meaning you don't have to care where the attachment upgrade is whatsoever. This fixes a well-known issue of needing to have the attachment in your hand when a minion is on the board. Air Strike gives you the attachment at the exact time you need it and you have full control over what and when you do.

Currently, it pulls out Marked and Suppressing Fire from the Aggression Aspect. There's no Neutral upgrade that can be attached to a minion, but these two are already good enough. 2 allies and 3 attack events in Aggression have synergy with upgrades attached to minions.

Glob and Shark-Girl love them both equally. Same with Surprise Move and Coup de Grâce, where the former is better suited to someone with high enough attack that can leverage readying well, while the latter is an outright insta-kill that can save you from some nasty 'When defeated' effects. Take That! will probably benefit more from the overkill dmg, as most minions don't have that much HP. If you don't care about the overkill dmg, you can always benefit from a little healing action. In all of these instances, there's a ton of synergy to be had with various other effects, such as damage buffs and excess dmg shenangins, all enabled thanks to Air Cover.

Am I crazy, or do I never see this card mentioned when people talk about how great damage increasing cards are for buffing multi-damage-instance cards? Such as Aggressive Energy, Warrior Skill, Float Like a Butterfly, etc. This card is already great, but it seems that buffs can really launch its damage.

Keep Up the Pressure is one combo I really have my eye on, since Wanda thwarts for 2, and it would allow her to summon this back from discard. Since it's a Side Scheme, you can "set it and forget it" if you happen to draw it early. Just wait until you cast the spell once, and then fish it back next turn at no cost but to thwart.

This guy is one of the strongest allies in the Aggression pool for sure. Yes, there are many candidates that deal higher amounts of single target damage, and some that go through a process to deal some kind of AoE. But Two-Gun Kid provides raw power, without the extra steps, without anything else but a single minion needed on the board. Dealing 2 against one target and 2 against another is amazing value, which can be taken even further with Boot Camp to essentially turn him into a Melee generator, or even more with Sidearm. The fact that he's an Avenger is also a huge plus - probably the most frequent trait to use with Team-Building Exercise. There is also Avengers Tower to discount him in an Avenger-heavy deck. Two-Gun Kid is one of the few allies in Aggression that makes it worth keeping a First Aid around for a consistently good damage source that doesn't rely on some random factor or rare niche scenarios.