Ravnica
Ravnica is a plane in the universe of Magic: The Gathering. It's essentially a giant city (in fact, its tagline is "City of Guilds"), continuously expanding outward and upward (rather like the hives of Warhammer 40,000).
Guilds
Ravnica is run by ten guilds, each of which embodies two of Magic's colors:
- Boros
- Red and White. THEY ARE THE LAW.
- Selesnya
- Green and White. A nature cult that brainwashes people who join it.
- Golgari
- Black and Green. Zombies, zombies everywhere.
- Dimir
- Blue and Black. Necromancers, ghosts, and such.
- Orzhov
- White and Black. They act like a church, but they're really all about the money.
- Gruul
- Red and Green. Not so much a unified faction as a bunch of clans of Chaotic Neutral anarchists.
- Izzet
- Blue and Red. Mad scientists, wizards, and inventors, ruled by a dragon. They're a little fuzzy on the idea of "safety".
- Azorius
- White and Blue. Boros may be THE LAW, but the Azorius Senate is the legislature and court system.
- Rakdos
- Black and Red. They're a Chaotic Evil pleasure cult (cf. Slaanesh), but the other guilds keep them around for cleaning up loose ends.
- Simic
- Green and Blue. They maintain what remains of nature on Ravnica by adapting it to fit with industry and civilization.
Tabletop
Ravnica was first featured in the card game with the Ravnica block in 2005 and 2006, which was in turn composed of the "City of Guilds", "Guildpact", and "Dissension" sets. The block was accompanied by the "Ravnica Cycle" trilogy of books, one for each set.
More recently, Wizards of the Coast has released the "Return to Ravnica" block, with the "Return to Ravnica" set released in October 2012 and "Gatecrash" in February 2013.