http://store.steampowered.com/news/10852/
Seems the page isnt up yet though, im guessing it will soon.
Dungeon Defenders - The Tinkerer's Lab Mission Pack, all new content for Dungeon Defenders is Now Available on Steam and Free for a limited time. Embedded within the floating islands of Sky City, the Tinkerer's Lab is the birthplace of the Series EV. Her creator, the Tinkerer, has been preparing for a chasis & software upgrade to EV 1.5, but harnessing the Eternia energy has attracted unwanted attention! *Offer ends June 26th at 10AM Pacific Time
Seems the page isnt up yet though, im guessing it will soon.