Completely disappeared without a trace. And deserters, who should have been brought back from previous installments of Heroes.

Why do you need this Swamp? I think that the "yin-yang" principle, the principle of opposition, should also apply to heroes. For example: Humans-Demons, Elves-Dark Elves, Mages-Undead, Dwarves-Barbarians (coming soon), Swamp - ? See, it doesn't fit.