After looting the dopplegangers (50 gp total) the party left the area, rested, and the next day ran into a inn in the middle of the woods, with no road leading to it. There was music and light and laughter inside. Eventually the party entered to find it was far bigger on the inside than the outside, with all sorts of people of all sorts of sizes . . . including the Bard!
They were at the Inn of All Worlds, a place for adventurers of all types from various worlds to swap stories and recuperate. On hearing that their own world was to be destroyed soon and their quest with the egg, a Storm Giant told them to seek the Horn of Summoning (which can only be blown once) which would summon everyone at once (and perhaps could be controlled more finely). A wise person called Sardak was said to know where it was and had been in the inn before, so the party asked to go where Sardak was dropped off (since the inn can travel).
They ended up in a desert near mountains, about 400 miles south of where they had entered the inn. They saw caves in the nearest mountain but were attacked by a whirlwind! They were able to communicate with it and found out that it was trapped her by Sardak centuries ago. It wanted freedom and the party agreed to find the seal in a cave the bound it and break that seal.
After fighting some skeletons, they found a book on how to become a lich and a jar with a seal, which (on breaking the seal) contained some scrolls that talked about three artifacts: A wand that influenced undead, an axe related to dwarves, and Horn of Summoning, said to rest in the castle of Skartos (who had inherited from noble and good ancestors, but who himself was cruel and evil), 200 miles to the east.
The party also found a fountain of green liquid, which had random magical effects, so the Paladin, Bard and warlock drank their waterskins and filled them with this random potion (the ranger declined and the ghost isn’t much of a drinker these days). They decided to rest in the cave mouth of the 3rd cave, where all of this stuff was.