It looks a nice replacement of the 4th edition of D&D. From what I see, it looks pretty mature already.
While I suppose they aren't your "target", 'cause you aim to the classic squared maps encounters, I suggest you to implement a sort of "extended challenge", so useful to recreate action scenes like chases, or dynamic combats.
Finally, I see that you didn't put rules for "flying creatures combat". I mean, I know that you simply can count the squares up in the sky, but that can be boring, and can lead to classic problems (ie. flying characters interact in a very limited way with all the rest of the map, usually simply sniping from above.
I humbly suggest you to take inspiration from the AGE system rules about the flying combatants (you can find them in Fantasy AGE, Dragon Age RpG and other that use that system). They are pretty fast and cinematic.