Dragon's Maze

[Thrillho]

Set 3 of 3 in Return to Ravnica block will be Dragon's Maze.
C&P from the Wizard's site announcement:
Set Name Dragon's Maze
Block Set 3 of 3 in the Return to Ravnica block
Number of Cards 156
Guilds All ten
Prerelease Events April 27-28, 2013
Release Date May 3, 2013
Game Day May 25-26, 2013
Pro Tour Dragon's Maze May 17-19, 2013
Magic Online Release Date May 13, 2013
Official Three-Letter Code DGM
Twitter Hashtag #MTGDGM
Design Team Alexis Janson (lead)
Mark Rosewater
Erik Lauer
Aaron Forsythe
Shawn Main
Dan Emmons
Development Team Zac Hill (lead)
Erik Lauer
Mark Globus
Mark Gottlieb
Masami Ibamoto
Sam Stoddard
Languages English, Chinese Simplified, Chinese Traditional, French, German, Italian, Japanese, Korean, Portuguese, Russian, Spanish
Available in Booster Packs, Intro Packs*, Event Decks*, Fat Pack*
(Not available in all languages)

The preview includes an image
of Ral Zarek, anticipated presumably Izzet-based Planeswalker spoiled through a DotP file hack, standing in front of the Ravnican skyline and adjusting his Mizzum gauntlets.

Full announcement here.