According to TibiaWiki BR, there are 4 stages to The Mummy's Curse World Change (aka Horestis' World Change)
1st stage: "Horestis near Ankrahmun is slumbering in his tomb. I wouldn't disrupt his sleep if I were you - this might be better for us all. Seriously."
2nd stage: "The great Pharaoh Horestis near Ankrahmun has risen from his slumber to crush all intruders."
3rd stage: "Horestis's body has been desecrated. His curse now hangs over Ankrahmun like the shadow of the vulture and his tomb is almost empty."
4th stage: "Horestis's body has been desecrated. By now, his curse has ended though. His minions are recovering slowly."
What type of creatures can I find on each floor in each of these 4 stages? Do creatures change only after the next server save or as soon as a certain stage is active?