Flavor wise, I’ll leave you with the description given by the Magic creative team.

Vampires live openly in Guul Draz and are famed for the decadence and perversion of their lifestyle. Bloodchiefs, the progenitors of their race, control the opulent city of Malakir. Vampire society is divided by “family” allegiances, each family beholden to its Bloodchief. Each family controls a small amount of territory and routes through the swamp, although the main currency of any family is in its connections and relationships. The tastes and passions of the Bloodchief tend to be imprinted on the vampires he or she creates.

There are five greater families in Guul Draz: Nirkana, Kalastria, Emevera, Urnaav, and Ghet. Dozens of other lesser families are scattered across Guul Draz, each with a contingent of undead nulls appropriate to their place in vampire society. Whenever a vampire fully drains the blood of a living creature without destroying the husk, a vampire null is created from the body. If nulls are left without orders, they will hunt and kill living things that they can find.

-Magic Creative Team, A Planeswalker’s Guide to Zendikar

Guul Draz Vampire XML

Guul Draz Lacerator XML

Guul Draz Bloodletter XML

Guul Draz Null XML

Tactics

Nulls swarm enemies, attacking mindlessly and attempting to maneuver to give flanking bonuses to the true vampires. The bloodletter dances through the melee, attempting to keep as many foes bloodied as possible at all times. Lacerators use their claws only as a last resort, prefering to grab and bite their enemies even when the enemy isn’t bloodied. The vampires stay hidden until someone’s bloodied, and then concentrate on the bloodied foe(s).

The Brothers in Exile are a group of “monsters” which seek to live peacefully. The brothers include lycanthropes, intelligent undead, intelligent beasts, and others whose mere appearance is enough to get “normal” people up in arms.

They were founded by a minotaur named Zortago. Zortago actually had a home, once. He’d been secretly sleeping in a barn to wait out a terrible storm, when he heard people shouting for a lost child. Zortago snuck out to search for the boy, and found him at the same time as the townspeople; the boy was pinned under a tree in a small depression which was rapidly filling with water. He lifted the tree, allowing the boy to slip free just in time to avoid drowning, and he was allowed to stay in the town ever since.

Things were okay for a while, but peoples’ memories can be short, and soon some of them grew to distrust him. Eventually, the family which had put him up found themselves at odds with the other townspeople, and though the boy and his parents implored Zortago to stay, he left so that they could find peace.

Through his travels, Zortago eventually met a wereboar named Lysander, who’d been thrown out of his village after contracting his condition, and a ghoul called Jhourgmand who took pains to only eat the carrion left behind by the kills of other creatures.

Today, the Brothers in Exile operate three monasteries. Zortago and Lysander each head one, and the third is headed by a vampire named Kelstas. Zortago’s monastery is located in a valley and provides aid to several nearby villages. Lysander’s is located near the summit of a mountain, far from any civilization. Kelstas’s is located in a forest replete with wildlife and caters to those with special dietary requirements, like Jhourgmand and Kelstas himself.

Encounters with The Brothers in Exile

The PCs’ benefactor tells them of a haven of evil not far, where horrendous creatures congregate and terrorize the hillside, lead by a ferocious minotaur.

A PC’s loved one is dying of a disease which can only be cured by a mummy, and he learns there may be one at Lysander’s monastery.

The Moneylenders is headed by Lord de Blays, and as the name implies it is a guild of bankers. The guild’s reach is far and as a result its coffers deep, for it is actually quite active all throughout the country and neighboring states as well. A moneylender agent can be found in every large city and many smaller ones as well, and offer travelers a safe and convenient way to store and transfer funds. They also make many investments, including backing both business ventures and exploration. Of the three vampire lords, de Blays schemes the least and seems more or less content to run an honest trade.

The Shadow Guild, headed by Lord Marchant, is well known to be involved in many highly-illegal activities, but it continues to exist because it would be incredibly difficult to oppose. Marchant has spies everywhere, it seems, and if he cannot bribe you he’ll kill you. The Shadow Guild facilitates everything from gambling to protection rackets to slave trading.

Lady Puchot of the Crafters’ Guild originally hailed from Shentreau. Her background is less a mystery than the other two vampires; it’s known that she was one of the first great artists to emerge from the city. Her art gained her the attention of another vampire, and thus gained her her immortality. The Crafters’ Guild reaches out to artisans of all types and has established trade schools in some of the larger cities. Lady Puchot herself seems nice, and is quite lovely, but she gives off an intensely ominous vibe. No one can quite put their finger on it, but any who meet her immediately get the feeling that she has some great scheme working.

Each of the guilds is quite wide-spread, and so many find it odd that the three would all be based in an otherwise-unassuming city such as Rastonia. This leads many to believe that there is some connection among the vampires, but if there is it is unclear.

Encounters with The Vampire City

Lady Puchot, having heard about a wonderful new talent in Shentreau, could hire the PCs to bring her the artist known as “M.”

The PCs find a gang of thugs harassing an old woman who runs a pottery stand. After sending them off, the thugs warn them that they’ve incurred the wrath of The Shadow Guild. Sure enough, they soon find themselves being targeted by thieves, leg-breakers, assassins and worse.

Lord Marchant hears about a particularly daring and skillful bit of thievery performed by one of the PCs, and invites the character to Rastonia. Marchant wants to recruit him, and will not take no as an answer.

Despite relatively sophisticated magical techniques, someone is forging counterfeit letters of credit and defrauding The Moneylenders of large sums of gold. Lord de Blays hires the PCs to find out who’s doing it, how, and to put a stop to it by any means necessary.