The characters listed above are all op compared to the other characters and are the "meta" and lately I've played teams with four of those characters which can just steamroll.
Buttercup: is a mess due to having crowd control and insane damage this would be ok if she wasn't as insanely fast and tanky so I recommend either nerfing her mobility or her damage output.
Cass: her ability to deal insane amount of damage with her ult blade dance she can destroy all non tanks health and with healers who are underpowered she can't be stopped.
Daemon: is balanced besides my one problem with him which is he has to much health combined with his mobility which allows him to escape almost any situation.
Zerocool: he outclasses all other healers and his healing beam is debatebly more powerful than Nikos life force ultimate which makes his healing the only good healing in the game.
Nidhoggr: he deals way to much damage and when combined with Zerocool he's basically unkillable his ride the lightning ability affects way to much space around him and leads to him being able to stop a while team from moving instantly.
All of these characters are op and will continue to be the only meta unless they are fixed or the other characters not listed are buffed this is a problem because it leads to the death of a game and I know for certain me and my friends are quickly losing interest in playing this game because of the lack of variety in team composition.
Hopefully these issues can be addressed I think this game has potential to be a great game but in it's current state it needs a lot of work to get to that point.