Path of Exile: Ultimatum Released

The new Ultimatum expansion is now available for the PC edition of Path of Exile, Grinding Gears' free-to-play action/RPG. There's a lot to know about this and this page has an overview along with a timer counting down the seconds to the release of the console editions next Wednesday. Grinding gear has details on Ultimatum Challenge Rewards, Game Balance, Item Filter and Passive Tree Information, New and Changed Gems, and All Rebalanced Essences. The Official Trailer offers an official look at what this entails. There's also a Q&A with Chris Wilson Video and Baeclast #68 with Lead Designer Rory Rackham video. Here's a concise explanation:
Significant updates have been added with the Ultimatum expansion, including the addition of the Trialmaster and his high-risk, high-reward challenges, Inscribed Ultimatums which provide great rewards to players, revamped reward systems as well as new Skills and Support Gems which are themed around blood and provide players with powerful skill advantages.