The multiplier dice are so, so absurdly broken it's hilarious. The fact that they stack as well makes the game's balance break in half. After the first boss, I was quickly in a position to simply farm up money, from which point I became completely unkillable. Any time an enemy would get close, I'd simply reset back to max shields, and then proceed to farm even more money.
Upon reaching the final boss, I had 3 die that all had 4x on every side, and one that simply had the spread attack on it. I hit each of them for 132 damage. It could have been more. The game is absurdly easy to break, but extremely fun in concept! Just needs some balancing.
Honestly, it's probably best to remove the gem faces - the idea of adding risk/reward with them is good, but it's far, far too easy to stabilize and then break the game in half.