Very well made game, I didn't expect anything less from this team, but I'm still impressed! Great graphics, awesome sound (both music and sfx), love the animations, and the gameplay was smooth. That said, the game balance itself is a little off.
As far as I can tell, there's no reason to block if you can heal instead. And I found, especially after a boss or two, there's no reason to block altogether. You have so much health you can just swing until you get some damage before using defensive dice. The only time I'd ever place a dye in blocking is when I had a turn off to heal to full and the enemies defense was high than an attack no longer mattered. Perhaps a mechanic where blocked damage is partially countered, or simply counts for more would make for an interesting trade-off.
The second problem is the "seven" mechanic. At first you have so few dice doubling literally never makes sense, and at 4 dice it almost never makes sense (15/36, of which most are very marginal benefits). Then at five and six dice instead doubling is almost always possible and net positive, making it a no-brainer too. I suppose the only way to really circumvent is, is to have a unique effect, e.g. putting in 7 now, deals/heals X damage in Y turns or gives you +2 to block (or a random stat) for the rest of the battle.
Also, a minor thing that's probably mostly me, but because the doubling of points is only shown after all dice are put in, especially the meaning of the enemy die is hard to see (unless you mouse-over it, which for whatever reason did not occur to me in my playthrough, likely because I can't interact with it myself). I had guessed the effect correctly even without the explicit explanation though, so in that sense the UI was clear :)
Finally, if I'm not mistaken, if you heal and kill on the same turn, the heal does not count. Even though it shows in the battle (e.g. from 25 to 30), the next battle starts with pre-final-turn health levels (25).