"A Mysterious Treasure" is a quest in the "Side Effects" premium module.
While wandering around the Temple Quarter, Geralt meets a drunk by the name of Drevin who seems to be feeling rather worse for wear after a doubtless not unusual night of carousing. Apparently the hangover cure he swears by is buttermilk. There is no accounting for some people's taste, nor for home remedies. The drunk tells him that in exchange for a jug, he will tell him about a magic stone which is also a portal to untold riches. Geralt decides to take pity on him and offers to give him any buttermilk he might find, doubting sincerely that any treasure exists.
As luck would have it, buttermilk is not so hard to come by for a witcher with a few different money-making talents and an interest in chatting up the general populace. Our hero then returns to his new acquaintance and gives him the jug. A grateful Drevin then tells him that he can find this magic stone in an abandoned mages' warehouse in the slums and gives the witcher a key.
The magic stone turns out to be a wayfarer's stone. Again, Geralt's vast experience provides a good idea on how to use said stone: a combination of three signs. A few tries later, he stumbles on the correct combination and voilà! he is teleported to some underground elven ruins which are not surprisingly guarded by a few nasty wraiths. Once the spectres are dispatched, Geralt finds a treasure-filled trunk near a throne. He then uses the twin wayfarer's stone and the same combination of signs to return to the warehouse.
- The combination for the Wayfarer's stone is three times Aard.
Looks like Drevin has a mammoth hangover. If I do him a favor by finding some buttermilk for him, he'll let me in on the location of a treasure, or so he says. I don't know if there's much truth to the drunkard's ravings but it might be worth a shot. I need to find some buttermilk for Drevin.
I have the buttermilk I promised Drevin. We'll see if he was telling the truth. I should give Drevin the buttermilk.
The drunkard wasn't lying after all. He gave me the key to an old warehouse. He claims mages once stored their artefacts there. For some reason they were forced to vacate it in a hurry and left behind a mysterious stone. Supposedly, if I cast the right combination of Signs at the stone, it'll teleport me to the treasure. I must find the magic stone in the mages's storehouse.
I figured out the right Sign combination: Aard, Aard, Aard. I need to look around for the treasure and then find a way to get back. Maybe the same Sign combination will work on the stone on this side. The treasure Drevin mentioned should be somewhere around here.
Failed quest Edit
I should fetch Dandelion and get him out of Vizima as soon as possible. I won't have time to finish this quest. I won't be able to finish this quest.