Among the rewards after completing Heart Of Destruction Quest we get an item called Spying Eye.
01:24 You see a spying eye.
It weighs 4.00 oz.
It shows which portals are open at the moment. As I remember in case of stronger monsters, their portal changes each 2nd hour counting from server safe into one random portal (Zao, Svargrond, Darama).
But how does the Otherworld works in case of weak - instable and stabilizing monsters?
Sometimes I can see both portals opened, sometimes none.