Great idea, some tweaks
There's a lot to be done, but it's a great start. MP consumption should occur ONLY if the user chooses, so set the gems, roll the dice and then choose whether you want the mp to be consumed because the gem met the conditions of the gem.
I made it to the end, but only by the skin of my teeth. Health gain needs to be improved. MP consumption should be a 1 always especially with how much luck is involved. There's no way to get a significant health gain when you need it.
Get rid of the pop ups to tell me the results, move it into a scroll box that lists the dice rolls and results, reduces clicking and cleans it up.
Holding the roll button doesn't really do anything for the player, no animation, just a sound playing, doesn't even really matter because it's all luck based. Should just be a click.
Oblivate was the only reason why I was able to beat boss, gave me +2 on 5 and 6 rolls.