I like it and I think I will enjoy the strategy behind it, but it has a lot to grasp. Do you have any thoughts about communicating everything to the player more smoothly? That seems to me like it would be the big hurdle and I'll add some thoughts. (And it turns out I took a while to stop. UI design/usability is complex

)
Clear, easily communicated changes:
Remove health/energy bar borders to make the actual informative bit bigger. Could make the bars disappear when full.
Make panning easier. Screen edge panning or click + drag should both work fine, maybe do both. Actually, I can't even figure out how to pan at the moment!
Zoom should probably support middle mouse control.
I'd almost skip zooming entirely and try working with everything being bigger all the time. It would help heaps with reading damage/ability text and seeing sprites properly. In the long run, allowing the player to choose a resolution would be fantastic to offset this.
If you make it bigger, you might be able to actually have the energy bar as pods - IE you can actually see that you have 9 energy left because there are 9 dots, possibly with grouping for easier reading.
In general I think a whole lot could be taken from the Desktop Dungeons unity beta (and some of the above suggestions are from there). They introduce a huge number of classes in a slow but interesting way and do quite well at displaying information to players - not just the UI but the unit sprites which are all extremely distinct. This applies to things like "fields" too - just stick a symbol on them.
The ability UI is okay and in the end I think it suffers a bit from the amount of information you're trying to cram in (8 abilities with costs, complex descriptions, times you can cast it different recharge rates). Not unmanageable, by any means. So uh, here's an awful ascii mockup that would probably be better:
---------
| |
| Attack |
| |
|X |
|0 /// |
| --- |
| /// |
---------Q
If I'm actually good at this, the information will be obvious but I'm probably not, so we have:
Use counters on the left. Adds to current version by showing maximum uses, and is much more obvious when it changes (crosses should be red or some other obvious colour)
Little lightning bolts = energy use.
In my mind, the hotkey Q ONLY appears when you hover over the button, but players might not realise it's actually a hotkey. Anyway, a tooltip or making it actually say "hotkey" as well might be handy, but (correct me if I'm wrong) you shouldn't need that information all the time - hotkeys are useful
because they're memorised.
The descriptions up the top actually work quite well for their format - to improve significantly on that, you'd need a semi-graphical way of displaying them. I'll leave that to you as you actually know what the "language" would need to describe

Finally, a possible bug: There was some odd behaviour when using "restore" - It seems to do nothing, but use lots of mana. Not really sure what's going on there.
Uh, so, I hope it's helpful because the strategy seems to be cool.
