Pacify the spirit of Gleb's brother???

[Mithrio]

I have a problem, my last quest is impossible(?) to solve... I have already been to the other Dimension to wipe out the Savirs, and got the quest to pacify the spirit of Gleb's brother after that. But I can't get back into the Dimension, because the soldier closes the portal after finishing the kill the Savir soldiers in the other dimension quest. If I ask him to get me into the dimension again, he says he can't because of the magic sponge which is in the treasury, right? How do I get in there, and is it still possible to finish this quest. Please answer... Please

[Catacomber]

Try with personality greater than 45. But if you killed the Duke of Poltergeists, you can't go back.