Keys and Infernal Machines:
Note that you have to be at Torment I or better if you intend to farm these. You need one of each of the four keys to make the new Infernal Machines – at a cost of 100,000 gold – but you do at least get to choose which of the four portals. (This assumes you have RoS, but is similar in any case if you don’t have the expansion). To open the portals start the act 1 campaign quest ‘Return to New Tristram’ and bash open the door behind Brother Malachi and use the appropriate device(s).
The recipe to craft the infernal machines can drop from any of the key wardens :
Odeg in the fields of Misery, Act I, who drops the Key of Bones
Nekarat in level 1 of the Silver Spire, Act IV, who drops the Key of Evil
Sokahr in the Dahlgur Oasis, Act II, who drops the Key of Gluttony
Xag’rith in Stonefort, Act III, who drops the Key of War
Infernal Machine of Bones opens up the Realm of Discord where you face Leoric and Maghda who drop Leoric’s Regret organ.
Infernal Machine of War opens up the Realm of Turmoil. Here Siegebreaker and Zoltan Kulle drop the Idol of Terror organ.
Infernal Machine of Gluttony opens the Realm of Chaos, battling Rakanoth and Ghom in return for a Vial of Putridness organ.
Infernal Machine of Evil opens up a portal to the Realm of Fright and the hardest fight, this one against Diablo and random Ubers. Drops Heart of Evil organ.
Once you have all four parts (and the recipe from Squirt in act II) you can finally make a level 70 Hellfire Ring which, like it’s predecessor is usable by level one characters and adds 45% increase to your experience bonus. Rinse and repeat for other character classes and/or better rolls. The whole process does rather highlight the repetitive nature of the game.
All this can only be completed at Torment difficulty, with the following chances :
Torment 1 = 25%
Torment 2 = 28%
Torment 3 = 33%
Torment 4 = 38%
Torment 5 = 43%
Torment 6 = 50%
Cautionary note : As you can see, unlike the ‘legacy’ Hellfire ring you cannot choose the primary stats, so you might want to craft it on the character or general class it’s intended for.
I’d test it thoroughly myself except, really, it’s just not worth the effort. Repeatedly kill a keywarden over and over again to get a key then, having spent possibly hours for this, repeat for the other three keys. Then face the bosses that may or may not drop the parts you need – and repeat this for each of the four organs you need. After all this you get a random ring that might have awful enchants – especially given the outrageous cost to re-roll on rings and amulets. You could of course get in groups but you invariably manage to find individuals that claim to have portal machine of their own but leave after you’ve used yours. No thanks!
The ‘old’ Hellfire ring is still available if you don’t have the expansion – or if you join groups still doing those portals. The only difference is the random nature of the portals, the fights are a lot easier and there’s only 3 keys and portals to sort not 4. The other difference is Nekarat in level 1 of the Silver Spire, Act IV. At level 60 he can drop the recipe and a random key. Once you have the recipe you can ignore him – or farm him for keys if you like that level.