Joint tournament: Heroes2, HeroesLeague, HeroesPortal, HeroesWorld: Invasion of Ghosts.

I don't understand the part about the 5 days and the 4000 ghosts; there simply aren't that many on the map. There are about two thousand, yes, they "exist" there, but where do I get 4 thousand? The sequence of actions is clear; I acted accordingly. But the number 4000 raises questions...