Where can I find the keys and the plans for the infernal machine? [duplicate]

Solution 1:

According to Blizzard's article on the Infernal Machine:

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 will drop from Odeg the Keywarden in Act I - Fields of Misery
• The Key of Hate will drop from Sokahr the Keywarden in Act II - Dahlgur Oasis
• The Key of Terror will drop from Xah'Rith the Keywarden in Act III - Stonefort
• The Blacksmithing Plans will drop from Nekarat the Keywarden in Act IV - Silver Spire Level 1

Note that these only drop in Torment. The higher the level of Torment, the better the chance of getting one, up to 50% at Torment 6.

The plans are taught to your blacksmith, and only are needed once. After that, you just need the keys from the previous three acts, as using the Infernal Machine consumes it.