Azorius Senate
The Azorius Senate is a guild from Ravnica and featured in Dissension. They are the guild themed of the colors of blue and white. In the city, their purpose is to create laws and ensure that everyone abides by them. The parun was Supreme Judge Azor I, a human lawmage who wrote most of the original Guildpact.
The Azorius work with the Boros Legion and the Selesnya Conclave to enforce the law, and the Orzhov Syndicate provides advocates and law mages as defendants or accusers.
During most of the Ravnica storyline, it is presided by the human lawmage, Grand Arbiter Augustin IV. After his death, the new guildmaster is named Leonos II.
The seat of Azorius power used to be Prahv, the Spires of Order, a large castle-like structure of white marble. Prahv was destroyed in the climax of Dissension by the explosion of the crashed Boros angels' fortress-ship, the Parhelion.
They are technically the ruling government of Ravnica.