As most idle games, it gets repetitive after some time. You could add diversity as challenges, like, achieve 10k pixels in x minutes, or ascend with 1 in vitality, or monsters are only damaged by magic, and so on.
I see wasted potential. You could use lots of ideas, like different formations that gives bonus to different stats, races or classes that specializes or upgrades, different kinds of damage (physical, magical, fire ... ) and resistances to them. Things to make the player think on strategies to win, and not just keep upgrading.