Wizards of the Coast will release Magic: The Gathering--Journey into Nyx, the third set in the Theros block on May 2nd.  The 165-card set will be available in Booster Packs, Intro Packs, and Fat PacksEvent Decks will be released May 23rd.
Journey into Nyx follows Born of the Gods (see "'M:TG--Born of the Gods'") and is the conclusion to the Theros block (see "M'Magic: The Gathering--Theros'"), as well as being the final part of the Hero’s Path OP event. 

Wizards will support the release with the normal program of events.  Pre-release events will occur on April 26 - 27.  Launch Weekend will be May 2 - 4.  The Pro Tour Event will be held in Atlanta on May 16-18.  Game Day will be May 24 – 25. The final three “quest”  in-store events for the block-long Hero’s Path event will happen during the release period (see "WotC's New Block-long 'Magic' OP Event"), with Quest 9 taking place at Game Day.