First of all: Very fun game! As far as autobattlers go this is pretty much exactly what I'm looking for, aside from maybe more individual unit customization. Super super fun to play.
Second of all: Just grabbing the achievement from the light store didn't feel like enough of a victory to me, since I mostly just got my ass kicked until I had enough cash. I wanted to feel like I had actually 'beaten' the game even though it was endless, fortunately for me, I accidentally had this run;
Which I've decided to take as a 'win.' I just sort of hooked up a mage with some good items, got lucky with what traits the mage rolled at first, and quickly snowballed into insanity.