This was fun until the glitches
Seriously, the glitches are bad. I had fun with my blue combos, stack up 5 or 6 blue spells then add a finisher or two. But when I got to level 14 I chose a blue spell, Outburst, which says it's supposed to do 16 damage. But it actually does no damage and is just a taunt spell. So I was hoping to level up quick so I could replace that spell with another blue spell. But at level 15... no skills to choose. You can actually pass the screen if you click the lower right corner of the popup box, where the "continue" arrow would have been. But then you have to discard one of your skills and you only have 3 then.
But, then when you get to the next battle, there are "empty" hex slots that appear. I think those are where your level 15 skill would have been, but you can't do anything with them, not even throw them away. I was able to win that battle quickly, but if a battle had gone on longer I guess there probably would have been more and more empty hex slots until finally there would be no move you could make.
Fortunately, I reached level 15 shortly before winning the game, so it was no biggie.