Harmony - Troop Symmetry

So, it turns out that dwarves, elves, and mages can use all 4 elements, while humans can only use 2.

All races can use all the elements; the question is which one will be more advantageous for a particular faction. In the original game, Chaos was not very useful for humans, almost regardless of whether they invested in it or not (except perhaps for Ice Bolt or Magic Arrow in the early stages of the game). Now, there are interesting spells for them in various game situations (without investing in Chaos - Air, with invested Chaos - also Fire).
In the case of mages, it is natural that they are interested in all the elements, as mages do not specialize in any one element (although Air will still be of interest to them only at the beginning of the game, as will Fire - in the later stages of a normal game and when transitioning to the late game, it will be more beneficial for them to go through Earth or Water).
With the Elves, the situation is as follows:
Does not invest in Chaos - goes through Air
Does not invest in Chaos, but takes blue druids - goes through Water
Invests in Chaos - goes through Fire
Invests in Chaos and takes blue druids - goes through Earth
Due to their low magic skill and the ability to have units with the "Channel" ability in their army, Elves can correspond to all four combinations depending on their magic skill and skill level, and therefore they can use everything - this will depend on your build.