Terraforming. When it comes to defense, modifying the terrain generates an important advantage, and for this we only have a very simple tool, which takes an average of the selected area, which makes the task of modifying the terrain very boring and time-consuming. It would be much easier to have an action to elevate, and another action to reduce the land, while still maintaining the current tool that averages the area.
The game needs to be fun and dynamic and all points, and easier terraforming, will make the game much more interesting.