I love the concept and the art. This game is a really good proof of concept!
Here are some suggestions to improve it even more!
Having your movement take an entire turn on its own is very frustrating so maybe have each turn have a movement and attack portion. Otherwise half the time you are just trying to chase down an avoidant enemy or putting yourself in harms way to just be able to do a basic attack.
After each floor give a reward that "upgrades one of your die". By this I mean you could do something like give them an extra number 5 for their die so they can tailor their dice to their play-style and make it more skill based.
Have the spells have different formations.
Like I said, very good start! Keep going with the idea for it has a lot of potential!