Hi, you suggested ideas and i'll give you some.
Nature Mage
Storm Wind - I think you could change the size of the model of this ability to a bit greater. Back in reality, a very small tornado don't calls lightnings right? So I thought you could put some reality on this ability.
- And I have a suggestion for this ability, the units affected by the storm starts swirling around the tornado or pulled to inside of it, but continue taking lightnings.
Nature's Protection Seems that you didn't use the idea of Flame_Phoenix on this ability, though I think you can improve this ability a bit better. When the mage binds himself with a tree, the tree could transform into a ent to attack the enemys while the mage is recovering.
Architect
Archichaos - The ability is great but if you could do on thing like, instead of channeling, the architect could be able to move and the towers flies around him in circles damaging the enemys.
There is a bug in the Golden Strike abilitie. The icon in disabled mode is in green, so see if the path is correct.
The idea of construction is cool, but it would be better if the gatherer could take down the trees. There is few space to build, and the dead of trees is great for doing abilitys capable of opening path. I'll give an other suggestion about that later in this post.
Medicine Doctor
Wave of Restoration - I have an idea for this spell. Instead of having a healing link between units, the doctor creates a healing energy nova, healing the units affected by the nova. The AoE increases with the level of the ability and/or the intelligence of the doctor.
Other suggestions
-The abilities have a great cooldown, try to small it a bit.
-Almost of the abilities are single target, that reduces the devastion effect of a powerful hero, so if you want to change the trees to "mortal trees", I suggest you make another hero, a another mage this time, but this mage could be capable of doing spells of great AoE with massive damages (fire, earth, lightnings, etc).