Blizzard updated new patch and something changed in the new version. Keywardens still hold the important keys and will appear in the same levels randomly. Well, you will feel it harder to get through because now you get lesser exp than before and have to find some specific places. New hellfire ring has special effect of fire nova explosion (200% weapon damage) and adds 45% exp. It is awesome to melee characters.  You may like Diablo 3 ROS Hellfire Ring FAQs.

New Hellfire Ring Plan

 

During the reaper of souls beta the drop rate is 100% in all difficulties. Fighting with the keywardens is interesting and worthwhile. Usually you can get 2 keys from one keywarden.

 

 

Four New Demonic Organs

 

Get four different keys from the keywardens and use them to create new inferno machine. Each machine will open a portal which provides a new organ for hellfire ring. Drop rate 100% at present.

 

 

New Hellfire Ring

 

There is only one design for hellfire ring so you have no choice. 6 random properties and loot 2.0 system will make you get the primary stats of current class almost every time. You can enchant to change some properties by consuming special materials. If you get the ring by barbarian and plan to use it by monk, put it to the stash and let monk do it, or you'll never get what you really want. 
Hellfire ring is Bound by Pickup and requires level 70 to equip, so if you plan not to play ros, you won't get it.

 

 

New Hellfire Ring Crafting Material

 

Vial of Putridness, Idol of Terror, Leoric's Regret and Heart of Evil are required to craft a new hellfire ring. Each kind of material need one piece.