Yes, it's a provocative title, but this is how I am feeling about the new heroes.
Nightmist, Argent Adept, and Unity are all new heroes that bring new mechanics to the game and also new frustrations. While each of them plays very differently, they do not play well with others. This does not mean they can't play with others, just that certain hero combos make you feel like these heroes are working against the team instead of for it. This is not necessarily a bad thing by itself, but you need to be more careful with choosing your heroes now. No more randomized heroes unless you want to potentially help the villain out. On the plus side, it does increase player discussion (often with begging).
Unity can destroy other player's equipment willy nilly, and while it is polite to get permission from your ally first, it is not required. This can make her a bit of a bane for both the Argent Adept and Absolute Zero, especially if her build a bot cards don't come out and she is dependent on her allies for scrap. She also does not play well with Nightmist or Haka whose most damaging attacks will punk Unity's bots as well. This leads to a, "please don't do that right now, it will hurt my bots and I can do a ton of damage with them! Well I can do a ton of damage right now with this spell!," type of conversation. Who deserves to do glorious damage more? The situation my dictate which is better, but not always. As a shared adventure,This can lead to some strife with players.
The Argent Adept is Absolute Zero, the sequel. I prefer him to AZ as he seems to have more to do early on, but he is just as dependent on lots of cards in play to pull of his really powerful stuff. I often look at his hand and say to people I can do great stuff in 3 turns if we can keep my equipment out. That's great but most villains trash equipment and ongoings. To ramp him up, other players are chucking their stuff. Again, circumstances may dictate what the better play is, but sometimes it does not. Playing the Argent Adept, and Absolute Zero in the same group can be a disaster as both are very needy heroes. I am seeing that one or the other can be properly supported but not both
Nightmist, as mentioned above does not play well with Unity, and also does not play well with Legacy. He tends to make her hit point investment in powers too punishing. In fact, he can shut her down effectively while helping everyone else. While you can work around this somewhat (E.g. pitching cards to redirect the damage),it is what I would call anti-synergy. It's odd when a player is begging you not to galvanize.
So what's the tyranny here? It is that by creating new and interesting abilitie, these heroes actually limit the effectiveness of other heroes in a much more direct way than I had seen previously. Ra can really mess up absolute zero, but he can also synergize well with him. While galvanize can cause some problems with Haka, it impacts Nightmist far more. So the previous synergy problems were only minor issues while these seem much bigger.
I generally like to see how heroes can work together, not how they make each other weaker. I'm also not a big fan of telling people that they shouldnt't play "that" hero with "these" others. I still love the game, but I am wondering if you have to be very careful with deck selection now or you are shooting yourself in the foot.