Yup, it's happening! Thanks to the kind community of fan website/database Puzzle & Dragons X, we know in advance that the Taiko no Tatsujin collaboration dungeon for mobile RPG sensation Puzzle & Dragons will be available for the North American server players, starting from tomorrow!
Said dungeon will last for two weeks (until September 6th) and will feature a variety of enemies from the first Taiko no Tatsujin game for Nintendo 3DS, Chibi Dragon to Fushigi no Orb. Among the noticeable changes for the first English localization of the dungeon, there's a weird name change for Mekadon, which the in-game database seems to refer to as Mechadon (link).
There's no word on the dungeon heading to the European servers yet, but great part of the collaboration events heading the States usually makes it to the EU servers, even if being delayed by a few months. Stay tuned for any updates of sorts!
Then again if you need help I always have that shiny Horus for everyone to en-OKAY OKAY I'M LEAVING
UPDATE: Reports from European P&D players confirm that the Taiko no Tatsujin collaboration dungeon is also available in Europe, under the same time frame. Have fun!