As for the Dungeon Lords – they worship the Dragon of Darkness, not Chaos. It’s logical that Darkness would be their primary focus for Specialization, but since they specialize in Chaos, Chaos can’t be ignored either. Therefore, I think the path to Specialization should be through Darkness, Chaos, and Sorcery.
I didn’t mean that the Dungeon Lords should change their Specialization build.
I don’t consider myself a strong Heroes 5 player; I only play as Humans, Elves, the Mage, and the Necromancer. I don’t know how things stand with the other three races regarding Specialization, but I want to say that I don’t see the point in specializing in it for the High Elf, Human, or Necromancer because of their skill tree. Because a set of various disables, especially in combination with the right artifacts, is more useful and applicable in a wider range of situations... both against all enemy races and in clearing the map (especially if the map is complex, not just empty).
My recommendation:
Specialization should tie a race to the magic of its castle (one school) and to “non-combat” skills that are equally useful for all races – i.e., Logistics and Education. These three skills should be for everyone. Moreover, learning Specialization should not prevent the player from choosing which racial magic skills they want to learn... if this is impossible, then I think it would be better to go through the three main magic skills of the race (as it is now with the Dungeon Lords’ Specialization in Fire Magic).