We're doing things a bit differently for the Guilds of Ravnica Prerelease. That Saturday, 9/29, we will hold 4 Prerelease events (not the usual 3). Each of these events will run only 3 rounds. Then, Sunday, 9/30, we will hold 2 events and these will run 4 rounds.
For each event you will need to choose which Guild you want to play-
Boros, Selesnya, Izzet, Golgari, and Dimir. Choose carefully, as there will be a service fee if you want to change Guilds. Also, there are a finite number of spaces per Guild, per event, so register early to be sure to get the Guild you want.