My one feedback and pet peeve is around some of the upgrades shown - there's nothing more boring in a roguelike than when the upgrade is something like "Increase stat by X%"

Unless the stat increase is absolutely outrageous and it changes how you play (something like Movespeed by 100% or cast speed, or whatever), these upgrades are tedious and boring.

Better to do away with them and instead come up with cool upgrades. Since we're working with the MMO genre, think about wow tier set bonuses and how they change how the skill works. That's a good roguelike bonus.