From publisher blurb:
Before the Scoured Lands surrounding the City of Skull were picked through and emptied of treasure at the behest of the White Temple, they were considered an unnamed landscape filled with the ruins of three fallen civilizations: the Dwarves, the Orcs, and the Elves. Each civilization was felled through war with the Elves, for when the Elves had vanquished the Dwarves and the Orcs, they turned their wars upon themselves until all that remained was the City of Skull - alone against the darkness. The sun was banished, and the only light that reaches the land now is from three moons.
The Guild of Black & Gold - the Adventurer's Guild of Skull - sends venturers out into the lands around the city to explore ruins and recover treasure. Expeditions into the Salt Waste are expensive and dangerous. And the Guild has decided to drag an envoy from the Guild of Midnight & Silver - the Arcanist's Guild - out of Skull and into an Elven ruin. The Elves were masters of Portals - magical doorways that moved warriors and merchants alike from stronghold to Skull in an instant. Fragments of records recorded just before the final acts of the Witchking war imply that this ruin is the site of the last portal used to connect to the City of Skull. If the mandate of the Guild is to comb through dark lairs for ancient treasure, then they are going to find every tool they can to make sure their venturer's make it back to Skull.
What will your players discover when searching for The Last Portal?