Heroes 6 - Discussion

By the way, it turns out you're right – according to the developers' logic, demons should be immune to all fire magic. That's absurd.

But why is it absurd? If Armageddon is only available to demons, then the nature of this phenomenon is completely different from that of other fire magic spells. Inferno uses this weapon, and Inferno is also protected from it. It all makes sense.