The Infernal Machine is a device that once crafted opens a portal to another realm where you can face off against Uber versions of Diablo 3 bosses. It is also a required step in crafting the Hellfire Ring. Click any topic to jump to that part of the guide.
Getting parts for the Infernal Machine
Realm of Uber Bosses
Hellfire Ring & Amulet
Keys and organs can only drop on Torment 1 or higher. Below is the drop rate per Torment level.
The plan is a guaranteed drop off any of the keywardens
Other general information
The first Keywarden is found anywhere in the Fields of Misery of Act I. Odeg has the Molten and Jailer affixes and a fire attack that shoots three balls of fire. His regular attack is a ranged spear throw. Just remember that when Odeg dies he will leave behind a exploding ball of fire that can kill you!
Key of Gluttony - Sokahr the Keywarden
The second Keywarden is found anywhere in the Dahlgur Oasis of Act II. Sokahr is a very anti-ranged monster as he has Missile Dampening, Mortar and Electrified as base abilities. His non-special attack is a spin attack that does damage to all those near him.
Key of War- Xah'Rith the Keywarden
The third Keywarden is found anywhere in the Stonefort of Act III. He has the ability to teleport and periodically rain down corpses that explode causing a fair amount of damage while also creating a small area of ice that slows you substantially.
Key of Evil - Nekarat the Keywarden
The last Keywarden drops the Infernal Machine Plan. He is found anywhere in the Silver Spire Level 1 of Act IV. Jailer, Knockback and Nightmarish are his main affixes along with a curse that reduces healing effects by 75%. Nekarat also has the ability to create a large firey spell on the ground that deals damage to anyone inside of it.
Note: He has a small chance to drop any of the other keys from a Keywarden.
Entrance to the Infernal Machine
Once you have all the materials you need to visit the blacksmith to create your Infernal Machine. After that it's time to enter the Realm of Chaos. The entrance can only be found on the last quest of Act I, "Return to New Tristram". Simply make your way to the healer in New Tristram and attack the door behind him. Once inside all you need to do is right click the Infernal Machine item in your inventory.
In my opinion this is the easiest of all the Uber bosses. There is no changes to these bosses that I noticed and it's basically just fighting both Ghom and Rakanoth at once. In all my runs I killed Ghom first as I found it to be quite annoying having the entire room fill up with his poison clouds. This fight is easy enough where anyone with decent gear should not have any trouble.
This match up is a little bit harder than Ghom & Rakanoth due to the fact Zoltun Kulle has a lot of abilities that interfere with the fight. Getting caught in his slow time bubbles while Siegebreaker chases you down only to be hit by a Meteor from Zoltun Kulle is not fun. I decided to get rid of Zoltun Kulle first as his abilities have the biggest impact on the fight. I just had to make sure to dodge Siegebreakers charge and the fight was simple once Zoltun Kulle died.
This was the hardest fight for me and it is the only fight that changes the actual mechanics of the bosses. You have no choice but to kill the Skeleton King first because when Maghda hits 75% hp she will put a invincibility shield on herself until every single monster including the Skeleton King is dead. If that wasn't bad enough you have to deal with constant Arcane Enchanted beams everywhere, as the Skeleton King keeps raising Skeletons and Maghda shoots her bug cloud at you. Have fun!
Quick facts about the ring: