I can't read this card and not compare it to United We Stand. Since Mass Attack requires you to exhaust your allies, you obviously can't use them for the turn. That's comparable to using the 3 allies as normal, then healing up the consequential damage with United We Stand...for 3 resources fewer. Mass Attack adds in your hero's attack, but it's hard for that to add more than 3 damage, far from worth 3 resources. To top it off - Mass Attack has a big setup requirement of 3 allies that share a trait with your hero, so on a lot of turns, especially in the early game, it will be unplayable. Now, this is potentially an unfair comparison as UWS can regularly turn 1 resource into 4-6 damage, which is insane. You also might not be running an Avenger as your hero (but Avenger is probably the easiest way to get 3 allies and a hero with the same trait). Compared to other 3-cost attacks like Swinging Web Kick or Gamma Blast, Mass Attack actually does a comparable job. 3 2-ATK allies and a 2 ATK hero makes this deal 8 damage, and that's with fairly average stats. An exciting idea could be a Spider-Woman deck or a multiplayer game that can give your allies Enraged. Blade and Wonder Man are cheap allies that come to mind with high attack but steep attack costs that could also pair well with Mass Attack. This is a build-around card for sure, but it can fill a role as the heavy hitting attack event Leadership doesn't get much of.

While there is a slight excuse that players have comparing this card to United We Stand since more the half the heroes were Avengers when this box came out, it is now an exceptionally flawed comparison. Not only does it miss the fact that it's only on Skirmish 3 mode that United We Stand gives you 3 health across 3 characters the entire game (on expert, most of the game is spent on Stage II, not III), it ignores that retaliation would deal extra damage to each of your allies attacking on their own, non-avengers can utilize this card just fine, and that there are lots of leadership decks that boost the hero's attack, so this allows you to pull double duty of keeping your allies out longer and utilizing those turns where hero is packing higher levels of attack.

Once again, the thinkers out thought themselves on this one.

In the current environment of Sentinels capturing your chump blockers, Infinites getting stronger when you recklessly throw away allies, and way more Villains utilizing overkill so there are no guarantees that your allies will even prevent much damage. There is also allies like Colossus, Wonder Man, Blade, Giant-Man, Cannonball, Drax, etc, etc, etc, that have stipulations about there attacks that might not be met each turn but cards like this by-pass that.

This card was always better then branded, and if someone is keeping it in the back of their binder, they might consider breaking it out to allow themselves more ways to get around ally limitations and villain/minion defenses then they were thinking.