i made it to stage 23, and am unable to beat it. i tried replaying earlier levels, but you don't get any rewards. did some treasure cave runs, earned 100+ cave coins, so i went in the cave shop. the only thing of interest is the runes, but i can't find any info on what they do.
so am i missing something, or is this a "pay to proceed" thing.
also my hero is level 5, about halfway to level 6.