Wizards of the Coast has announced its next multi-platform Dungeons & Dragons event, The Tyranny of Dragons, which will launch this summer in some sort of proximity to the "hard copy" release of the new D&D rules, which is also due this summer (see "'D&D Next' Launch Date Set").  The epic Tyranny of Dragons Encounter for its D&D Encounters organized play program pits players against hordes of dragons led by their five-headed queen Tiamat, a ferocious villain from the Nine Hells who first appeared in D&D lore back in the mid-1970, and has been chosen for this special event which marks the 40th anniversary of the Dungeons & Dragons game. 
The Tyranny of Dragons event will extend across several platforms including video games, mobile games, and in-store play at local hobby stores.  This carries on the expanded, multi-platform strategy that began with the launch of the Sundering last August (see "Exclusive Interview on 'D&D: The Sundering,' Part 1").
While WotC is hoping to encourage retailers to use the most recent D&D rules (D&D Next, which WotC is now calling the "New Edition") when holding The Tyranny of Dragons events in their stores, it remains the storeowner’s choice whether to use D&D Next/New Edition or D&D 4.0 or even the older 3.5 (see "WotC Clarifies Next 'Encounters'").
ICv2 contacted WotC for more details and the company replied: "We do not have any additional information to share at this time, but we will be releasing details on Tyranny of Dragons products and organized play offerings in the coming months."