Thanks Human! I'm glad you enjoyed the game overall. And sorry for my late reply. Last week was incredibly busy.
As for adding more variety to a longer game: 100% agree, even though I'm not quite sure yet what to implement exactely without making the battles tedious and/or overly complex. I'm currently playing around with a few utility orbs (such as healing spells and orbs that change the enemy's weaknesses) alongside with one or two additional elements, but there is nothing set in stone yet.