The latest post on the Diablo 3 blog describes how the new Infernal Machine will operate once patch 1.0.5 goes live. Essentially, this machine must be constructed using parts scattered across Acts before it transports you to a boss room containing a pair of super-powered versions of Diablo 3 bosses. Coupled with the difficulty-raising Monster Power feature (also added in patch 1.0.5), it marks one of the toughest challenges Diablo 3 can offer.
Three pieces of the Infernal Machine and the smithing design are held by four Keywardens, one in each act. While these Keywardens can be fought at any difficult setting, they'll only have a chance of dropping one of the components of the Infernal Machine when fought at Inferno difficulty and with five stacks of Nephalem Valour. The chance of a Keywarden dropping one of these pieces can be raised by increasing the Monster Power setting too: whap it up to the maximum of 10 and, while you'll have your work cut out, you'll be guaranteed to have an Infernal Machine part drop. (Whap it up, by the way, is a technical term I'm coining).
With all three components in hand, your blacksmith can begin work on constructing the Infernal Machine portal device. Your blacksmith must have been improved to level 10 before he can learn the Legendary smithing plans. He'll also ask you to fork over 12,000 gold to create the thing.
Much like how the Staff of Herding only works at one location, the Infernal Machine can only be used in a specific cellar in New Tristram called the Heretic's Abode. Once clicked on, the machine is destroyed and in its place will sit a brooding, angry looking red portal leading to one of three realms containing boss encounters. This realm is chosen at random, though the pairings of bosses on the other side are fixed. To create another portal you must re-acquire the three Infernal Machine parts (you don't need the design again) and re-pay the blacksmith to construct another machine.
Who you end up facing is decided by the realm you're teleported to. In the Realm of Discord you'll find King Leoric and Maghda. In the Realm of Chaos you'll encounter Ghom and Rakanoth. And in the Realm of Turmoil you'll find the Siege Breaker and Zoltun Kulle. Blizzard say these battles will be "about as challenging as the Diablo fight in Inferno", with each boss retaining their usual skills and abilities, with a few secret augmentations on top.
Successfully defeating a pair of bosses will reward you with the chance to obtain one of the three parts of the Legendary Hellfire Ring - again, full Nephalem Valour is required and Monster Power increases the likelihood of these parts dropping. With all parts collected and the design bought (costing two million gold from a vendor), your jeweler can craft the unique item, which gives a guaranteed 170-200 stat to either dexterity, strength, vitality or intelligence, a +35% experience boost, four random magical properties and a "chance to launch an explosive Hellfire ball when you attack".
The ring is bound to your account, so will not be available on the Auction House. It also comes without a level requirement, making it an extremely useful tool for levelling up alt characters. And that's how the Infernal Machine works. To recap:
- Kill Keywardens for Infernal Machine parts and the smithing design
- Pay your blacksmith to build the machine for you
- Use the Infernal Machine to open a portal
- Enter the portal and kill the boss pair for a part of the Hellfire Ring
- Repeat steps 1-4 until you have all three Hellfire Ring parts
- Buy the Hellfire Ring design from Squirt the Peddler
- Pay your jeweler to build the Hellfire Ring for you
For more details, you should mosey or stroll on over to the official blog post. Patch 1.0.5 goes live in Europe at noon BST tomorrow, October 17, so put some pants on.