There is a new order in Mulmaster — my order. For too long, we have allowed ourselves to be second to powers like Zhentil Keep and Hillsfar. Under my guidance, Mulmaster will soon rise to become the dominant force in the Moonsea!»
— High Blade Rassendyll «Selfaril» Uoumdolphin


Geographical Overview
From the sea, Mulmaster looks captivating enough. A pirate once likened it to a gleaming pearl washed up on shore. Gabled rooftops, slender alabaster towers, and a thicket of wooden masts rise up behind the pale gray walls that neatly enclose the harbor and shoreline districts. The city crawls up the slopes of mountains that peak to its south, and set upon these peaks are some of the most majestic spires overlooking the entire Moonsea.
Mulmaster’s charm fades quickly as one navigates the overcrowded harbor or passes through the city’s fortified gates. Never mind the occasional body floating in the harbor, the dour guards at the gates, or the rotten stench! The buildings nearest the docks are dilapidated and weatherworn, the people here live in squalor, and criminals strike with impunity. Farther up the mountainside, where the air is fresher, hateful fences and intimidating walls separate the homes of the wealthy elite from the ghettos, and desperate beggars are openly berated and beaten in the streets.
The highest spur of land in mountainous Mulmaster is the site of the Towers of the Blade, a sprawling cluster of residential spires where the ruling families of the city abide in luxury. Here the guards are well paid and jovial, the cries of the poor are stifled by the chill north wind, and local law is written with bribes. Cloaked figures skulk about, but their business remains their own. One can easily fall in love with the world from up here, where the air is thinner and the people are fatter.
Mulmaster sits on the edge of a cruel, cold, rugged tract of land dominated by the western Earthspur and Galena Mountains. Although the mountains offer some protection against bitter winds and heavy snow from the north and east, they are treacherous to cross and don’t grant Mulmasterites safe and easy passage to the Unapproachable East. Most land traffic from Mulmaster heads south, along a well-traveled trade road that skirts the eastern edge of Cormanthor and plunges headlong into The Vast, east of the Dragon Reach.
Scores of despondent refugees from Zhentil Keep camp in shacks and shanties outside the city walls, relying on the uncharacteristic charity of the city’s corrupt nobility. Mulmasterites generally resent and distrust the newcomers, who take food from the mouths of poor city folk and offer precious little in return. Beyond Mulmaster, the eastern Moonsea region boasts little else in the way of settlements apart from a smattering of fishing villages, monasteries, and citadels.
The White River slips between the jagged Galena and Earthspur Mountains, heading east toward Narfell, Damara, and Impiltur. The black basalt fortress known as Ironfang Keep looms over the river’s mouth and remains a constant source of worry and consternation among Mulmaster’s nobility, although the dark wizards who dwell there have yet to raise a finger toward their corrupt neighbor to the west.
The Campaign in Mulmaster
The quests in this chapter are intended for characters of 9th-15th level. Presumably the PCs will wander into Mulmaster after having spent some time exploring the northern and southern Moonsea regions around Melvaunt and Hillsfar. In all likelihood, they have traded horses and seafaring vessels for teleport spells and other forms of expeditious magical travel, allowing them to hop between these cities as they please.
Mulmaster is a decadent sprawl riddled with crime and corruption. Mulmasterites believe their neighbors plot against them, and the city has long felt isolated from the rest of the Moonsea. Fear breeds intrigue, and nefarious schemes abound in Mulmaster. Characters who come to the city hoping to skirt the intrigues of the Red Wizards and the Zhentarim will be gravely disappointed, since both organizations figure prominently in the quests described in this chapter. Thay and Zhentil Keep have important long-term plans for Mulmaster, and PCs who meddle in their affairs might find themselves caught in the middle or impaled on the business end of an assassin’s blade.
Mulmaster is a predominantly evil place filled with evil people. Good-aligned characters should never feel entirely welcome or comfortable here. That said, Mulmaster needs adventurers as much as any city. To keep the PCs interested in Mulmaster (and to keep them coming back), you will need to tread carefully and allow them room to conduct their affairs without interference. If spies and assassins harangue them constantly, their interest in the city will evaporate. To help invest the PCs in Mulmaster, have the city reach out to them occasionally. Establish strong ties between the characters and certain individuals and locations within the city. For example, upon hearing that a new group of adventurers has arrived, clerics at the Temple of Tymora might extend their friendship by offering the PCs discounted healing potions and scrolls. Similarly, characters might bond with a morally ambiguous or morally challenged NPC who doesn’t regard them as a threat — someone who can help them navigate the city’s labyrinthine political landscape. Look for occasions to subtly alter the PCs’ perceptions of the people who live here. An evil noble might suffer a crisis of conscience and come to them seeking redemption. An assassin hired to eliminate them might spare their lives for no reason other than he admires their willingness to sacrifice all for a city that doesn’t deserve their affection. Paint Mulmaster as a city worth saving, and the characters might be persuaded to stay for a time.
In short, there isn’t much good in Mulmaster. With good folk in such short supply, evil tends to prey on itself. Several of the short adventures in this chapter revolve around the mounting conflict between the Red Wizards of Thay and the Zhentarim. As the story unfolds, characters will have opportunities to hinder and help both groups through their actions and involvement, even if Mulmaster itself cannot be saved.
Mulmaster on Adventurers League Wiki