The House Dimir, run by Lazav, the Multifarious, (on the outside) are responsible for running the cities libraries and information hubs, but on the inside, they are the cities assassins, mind mages, and information secret hoarders. The Dimir guild hall is the Duskmatle, a place no one remembers.

The Simic Combine, run by Prime Speaker Vannifar, are the cities scientist and evolutionaries. They experiment with life and grow it in unnatural ways. They somtimes let there creations out on the city. There guild hall is Zonot One, a massive hole leading to an underground ocean.

Before and for a short time after the signing of the Guildpact, the Gruul Clans were a wild and noble guild charged with maintaining the wild places on Ravnica. They were supposed to keep civilization in check. Civilization and the other nine guilds, however, overran every wild place on the plane.

The Orzhov Syndicate is the Ravnican guild of business, where the values of white and black meet and the dead exist solely to rule. ... The Orzhov guild is founded on the beliefs that wealth is power, that structure breeds wealth, and that guilt creates structure.

The Seleysnya Conclave, led by Trostoni (who has a special connection to the world soul, Vitu Ghazi), is the most peaceful of the guilds. There gardens are a safehaven to all, and anyone can join. There ranks are growing more by the second, and there guildhall, Vitu Ghazi, is a giant tree.

The Cult of Rakdos, led by the great demon Rakdos, are responsible for the pleasures of the city. They have massive shows that most of the time turn deadly. There guildhall, RIx-Maddi, is a giant palace underground where Rakdos sleeps for centuries.