This one was a real puzzler! The magical girl transformation sequence at the start was great and the way the actual mechanics tied into stone ocean was also unexpected but well done.
I think the underlying fundamentals of the puzzler are quiet solid. I had a good time breezing through until I hit a wall and had to sit and think, then did a few moves and it worked out. That's exactly what you want from this kind of puzzler. I'm impressed with the water displacement mechanics - perhaps it's easier in a proper 3d engine like unity than I am used to, but it's pretty cool nonetheless.
The main thing missing is bits and pieces of polish, mainly in the UI department. The exits early on aren't obviously marked (before the water mechanic is introduced). Also, the way that water is displaced if a block is summoned in it makes sense intuitively but there's mechanical elements, primarily to do with the gems, that are probably worth tutorialising or explaining.
I don't know if it's possible to trap yourself in a failstate and not realise it - perhaps an easy-ish way of preventing this is to allow players to rewind their moves (either placing or removing blocks) and reverting the water. Maybe this doesn't play well with the platformer mechanics, who knows, but it does seem a bit odd that players have to simply recognise when they've screwed themselves.
I also think the cursor UI is probably too small and slight than I would like, particularly when what you're interacting with is so big and how important it is to see how many clicks you have left.
Still, I really enjoyed it! Good job!