1. Let Waterwalk remove the movement penalty for snow, sand, and swamp, similar to Pathfinding of the corresponding level. This would be a sort of "mini-fly" in the water school at level 3. It would also be good to reduce the mana cost further.
2. I support someone else's suggestion mentioned earlier in this thread: I believe that a Castle Gate spell similar to Town Portal should be added to the fire school, and a Map Teleport similar to Dimension Door to the water school; then all schools would have control.
3. Finally, make all level 4-5 buffs mass spells for experts! Compare, for example, Prayer and Slayer: +4 attack, defense, and speed for all units, or +8 only to attack and only for level 7 creatures and only for 1 stack! By the way, Slayer could have become a situationally useful spell specifically for Dragon Utopia if it acted on all stacks at least.