How does the Efreet/Marid spawn work in Burster Spectres?

Question

As soon as you enter the Burster Specres spawn west of Darashia in the Haunted Tomb there is a Djinn corpse by the rope hole. Clicking this corpse will teleport you to an island that can spawn Efreet and Marid. I was wondering if there was any more info on this spawn.

• Is it completely random?
• Can they only spawn every hour after server save or any time?
• Does the "raid" always last for the same amount of time before they despawn?

Answer 1

It's completely random. Sometimes raid lasts 30 mins, sometimes up to an hour even.  I  was told that this changed, but I never went to check if there is still a raid or not. This is a matter of following the first information on this raid.

Answer 2

This is a raid of both djin, during 30 min, normally using for bestiary. I have no sure if is a raid like Oramond.