Anthem had mechanics like this with it's elemental combo/priming system. This might be more in depth, but the basic idea has been tried before in a third-person co-op shooter, and it apparently did not add enough to the game for success.
The main problem of the genre (looters) is that you actually need to nail a few things :
itemizations, stats and mechanics. And its incredibly complex to do, I'd argue that its probably the hardest genre to give a go to because you have to balance abilities (cooldowns, damage / utility) and stats between tier rarities and across different classes. Anthem's problem was that it UTTERLY, and I mean UTTERLY failed at pretty much all of this on top of having poor mechanics despite giving the player flying suits. Plus, the technical side of things was a disaster too in terms of performance for many. It wasn't even good for early access at launch as harsh as it sound.
Every single looter launched since at least 5 - 6 years has had or still has major issues in at least one of these categories. It took forever for Diablo 3 to find its footing (basically it took an expansion years after), Diablo 2 was in an extremely laughable state before its expansion, Destiny 1 and 2 I think its safe to say that both needed an expansion to iron everything out too. Torchlight 1 was surprisingly awesome from the get go, but 2 had issues. The Division was the first attempt at translating the genre as a 3rd person shooter experience, and in between we got the forever awesome Warframe which, lets face it, was also pretty bad at release lol (but is honestly amazing now and definitely a reference to look upon)
Grim Dawn, which can rightfully be considered as the major "foot forward" of the genre, also had issues because of its expensive itemisation / damage system (the usual, some elements were too underwhelming, minion builds were bad etc etc)
Honestly as of late only Outriders did it half correctly, and I'm saying half because 2 out of 4 classes in it were garbage tier at launch in endgame, yet everything's fine after, you guessed it, an expansion
Now, I understand that in the context of Rocksteady and the recent release of Avengers which ALWAYS played like trash from the beta, theres a certain level of disdain to be had because historically speaking, looters as a genre have been an insane roller coaster of expectations vs reality. Yet, as of now, the feedback of the Squad's closed beta has been nothing but glowing despite the showing in the State of Play. Somehow it seems that Rocksteady utterly nailed what will ultimately make or break the game on their first try.
And from what I'm seeing, it seems like they mostly focused on tried and true elemental damage system, with different traversal / shield mods, different ultimates for characters, what seems to be rather engaging conditions for gear bonuses (requires active play), and gear sets inspired by DC's vilains portfolio, which could lead to some really fun times.
Me I'm just hoping for a challenging difficulty option unlocked after the campaign is done, and worthy gear sets to collect. Also wondering if the leveling is global or on a per character basis, because I could be wrong but it seems that the former is the only good option to have in a game where you can switch from character to character on the fly in a mission without having power discrepancies while playing solo (player level / gear score). If that's the case, I hope that playing online is the way to level the heroes independently because fuck that noise
edit : I forgot the ONLY loot based game released as of late which didn't need anything but performance patches to iron out, and its Nioh 2. Its an AMAZING looter on top of having an excellent combat system
