The Infernal Machine is a portal device used to open a rift into a random location that will match you against two Uber Bosses. Each encounter has a chance to drop one of the four organ items required to craft the Hellfire Ring (Requires level 70).
How to Start
The Infernal Machine Recipe has a random chance to drop from Nekarat the Keywarden in Act IV: Silver Spire Level 1 in any Difficulty.
Once the recipe is looted, talk to Blacksmith Haedrig Eamon at any of the towns, then click the recipe in your inventory. The Portal Device will now appear under the Blacksmith’s Forge Weapons tab UI.