Diablo III: Reaper of Souls

This new thing, you use it to salvage a legendary item and it stores the item's passive ability in it. e.g. Unity's 50% damage reduction. You can then equip 3 legendary powers, one from a weapon, armor, and jewelery, but nothing from a different class. i.e. you can't wear another class's Hellfire passive or class specific ability.

The addition of Kanai's Cube truly is very interesting. I saved up lots of my immunity amulets (including my one and only poorly-rolled Star of Azkaranth) hoping they'd be useful someday. Hellfire amulet + poison immunity (Mara's) as a barbarian is something I can look forward to, assuming that's how the new cube will work.

Torment 10...I'm hoping they can raise the chance rate of getting keys from keywardens since I want to replace my old one. If they raise it to 100% chance of getting keys at T10, then I'd be very happy. Making a decent hellfire amulet, while we're all at the mercy of RNG for a good roll, will be less time consuming like ever before for those who like to solo such as myself.

I'm pretty sure most people are also very happy with the removal of Realm of Trials from this patch. We shall see more in the PTR!

EDIT: I just read through Travis' post about the Hellfire event. Keywardens will drop infernal machines themselves and the Hellfire Amulet will come with a built-in socket. This is amazing news!