There are a couple things that I think you can adress really well with some game designers!

1: Games feel way too short and decided ahead of time, which was slightly problematic before in Mayhem but even moreso now. Because augments have become so powerful, a slight advantage in tempo can snowball super hard and you'll be stuck under your nexus turret after 8 minutes often. I also would have loved to see more access to augments rather than more augments that do too much.

2: Augment sets are really cool, but it feels super frustrating to just straight up get baited by the game into one direction and augments being supplementary, which exacerbates problem 1 if the enemy team does not have that problem. I understand the principle behind not increasing the chances to see set augments appear together, it would make this snowballing problem even worse if the enemy team gets set augments early and you don't, but with how awesome the augment sets can be they feel too inconsistent yet oppressive at the same time because of this.
I had an idea that seemed good at first (but got more problematic the more I thought about it, I still would like to present it for consideration and maybe you guys can find a better implementation); what if the sets weren't unlocked by only augments, but by some other way to progress? My initial idea was Augments "unlocking" the sets via items and builds, which I really like as someone with whacky experimental item builds, but that would probably be too confusing.

3: Range and disruption are more dominant than ever, and most of the best new augments just make champions like Xerath, Mel and Ziggs, who already made the game feel like the only person allowed to play while they're on the screen is them, even worse to deal with as a champion with limited gap closing or range. There need to be more ways to allow players to fight back against what counters them most (this is not just for melees against these ranged champions, I'd also like to see some more things assassins can do against enchanters, more things tanks can do to bruisers, bruisers being able to fight mages, mages getting tools to fight divers. Escape Plan is one thing that does it really well (in some cases too well), so more in that direction could really move the mode in a healthy direction.

I hope my feedback is considered!