Keywardens for Infernal Machine - Finding the Keys

Keywardens for Infernal Machine - Finding the Keys

The Components

To craft the Infernal Machine, players will first need to collect four components from powerful Keywardens in each Act of Inferno:
  • The Key of Destruction drops from Odeg the Keywarden in Act I - Fields of Misery
  • The Key of Hate drops from Sokahr the Keywarden in Act II - Dahlgur Oasis
  • The Key of Terror drops from Xah'Rith the Keywarden in Act III - Stonefort
  • The Infernal Machine Blacksmithing Plans drop from Nekarat the Keywarden in Act IV - Silver Spire Level 1 (Note: You only need to farm the plans once) - Patch 1.0.8 Update: Nekarat will now also drop random keys!

Players can only encounter the Keywardens in the Torment 1+ difficulty and only with a full five stacks of Nephalem Valor will they have a chance to drop pieces of the Infernal Machine. While Monster Power is not required, each level will increase the drop rate of both the keys and the plans by 10%, all the way up to a guaranteed 100% drop chance at Monster Power 10.

How to turn on Monster Power: Go into Options > Gameplay and look for "Enable Monster Power Selection". There is currently a bug where the MP option turns off randomly, and you will have to go into the options and turn it on again. After enabling it, you can select a monster power level in the quest selection menu. (1.0.8 update, this bug seems to have been fixed.)

Each component will be considered “Bind on Account,” meaning they can be used by any
character on your account.

The Device

After all the components have been collected, they can be assembled in town at the Blacksmith. Your Blacksmith will need to be level 10 in order to learn the Legendary plans, and he'll require 12,000 gold to forge the device in his furnaces.
Once crafted, the Infernal Machine will remain in your inventory until activated.
Once assembled, the powers of the Infernal Machine can only be unleashed in one location -- a cellar in New Tristram known simply as the Heretic's Abode. To activate the device, start the quest "Return to New Tristram" and then enter the cellar (located just behind Brother Malachi the Healer) and right-click the item in your inventory. This will summon an ominous red portal that will lead you to a demonic realm where you'll be pitted against a pair of Sanctuary's most nefarious villains. (Note: Before you enter, make sure you get 5 stacks of neph, and Monster Power is set to a level you can handle. It is best not to start at a very high level as the Uber bosses are very tough.)
In order to access the Heretic's Abode, players will need to set their quests to "Act I – Return to Tristram." 
Activating the Infernal Machine will also destroy it, so to open another portal, you must craft the device anew. This process will include recollecting each of the three wardens' keys as well paying another 12,000 gold to the Blacksmith. (Don't worry about the plans -- once you've trained your Blacksmith, they will remain available in your crafting list for use at any time.)

The Bosses

Those brave enough to step through the Infernal Machine's ominous output will be transported to one of three randomly selected Realms of Pure Evil, where a predetermined pair of bosses awaits:
In the Realm of Discord, King Leoric and Maghda guard the Royal Crypts.
In the Realm of Chaos, Ghom and Rakanoth defend the Larder. 
Finally, in the Realm of Turmoil, Siege Breaker and Zoltun Kulle protect the Edge of the Abyss.
In terms of difficulty, the encounters will be about as challenging as the Diablo fight in Torment, and each "uber" boss will retain their full arsenal of base spells and abilities. Many of the abilities are more powerful, and certain bosses have even come up with new tricks to test those who dare to enter their domain.
If you happen to fall while battling one these Infernal foes, don't worry -- as long as you don't leave your game session, you can release and restart the encounter at any time by clicking on the very same portal you created. Similarly, even after both bosses have been slain, your portal will remain active in the Heretic's Abode until your game session has ended, which means that if you're out of inventory space, you're welcome to leave and return without losing your loot.
(Please note that you cannot be sent to the same Realm of Pure Evil twice in a single game session. This means that if you create or have access to four or more Infernal Machine devices, in order to use all of them, you'll need to start up a brand new game once you've opened up three portals.)

The Rewards

For successfully defeating a boss pair, players will be rewarded with extra items and gold. In addition, they will also have a chance to harvest demonic organs from each of their fallen foes, which can be used to create a Legendary item of unique power: the Hellfire Ring.
Three organ pieces will be needed to forge the Hellfire Ring:
  • The Writhing Spine, which drops from King Leoric or Maghda in the Realm of Discord
  • The Devil's Fang, which drops from Ghom or Rakanoth in the Realm of Chaos
  • The Vengeful Eye, which drops from Siegebreaker or Zoltun Kulle in the Realm of Turmoil
Similar to the wardens' keys, a full five stacks of Nephalem Valor will be required for the organ pieces to drop, and each level of Monster Power will increase their drop rate by 10%.

Each time you wish to craft a Hellfire Ring, you will need to present all three organ pieces
as well as 15,000 gold to the Jeweler.
Once all of the organs have been collected, they can be combined at the Jeweler using a new design available for purchase from Squirt the Peddler. This design will teach your level 10 Jeweler four variations of the ring: the Hellfire Ring of Intelligence, the Hellfire Ring of Strength, the Hellfire Ring of Dexterity, and the Hellfire Ring of Vitality. Depending on which variation you choose, your ring will be guaranteed to roll one primary stat with a set value range of 170–200.

Note about portals: If you  are having a tough time getting a certain part, remember that if you farm 3 infernal machines, you can open all 3 portals in one game. You can also find 2 or more other people with infernal machines, and then open them all in one game. That way you can get all the parts without having to do an uber you already got the parts from.
In addition to the guaranteed primary stat, each ring will always have the following:
  • +35% Experience
  • +4 Random Magical Properties
  • No Level Requirement
  • Bind on Account
  • Chance to launch an explosive Hellfire ball when you attack
The Hellfire Ring will be considered Unique-Equipped, which means that players can only wear one at a time. Your followers will be able to equip the ring, however, and given the boost to experience and absence of a level requirement, the rings make excellent heirlooms to be passed down to each of your alts. If you no longer find the need for one of your rings, simply salvage it for materials at your local Blacksmith. So create one or create more -- the choice is up to you!