Below you'll find a list of hotfixes for the month of October which address various gameplay and service issues affecting Diablo III.
Hotfixes are updates we make on our end without requiring you to download a new patch. Some of the hotfixes below will go live the moment they are implemented, while others may require a restart to go into effect. As always, please keep in mind that some issues cannot be addressed without a client-side patch update.

Bug Fixes

General
Bug Fixes

Bug Fixes
Monster power is not mandatory for receiving a key or organ but it is very much recommended.
1.) can keys actually drop without monster power enabled, as was suggested in the infernal machine blog? Or was this a mistake in the blog, and the keys will only drop in Monster Power 1 or higher, as was previously
suggested?Monster Power isn't required. At MP0, the drop rate for both the keys and organ pieces is 5%. At MP1, that chance increases to 10%, at MP2 it's 20%, and so on until MP10 (which grants a 100% drop chance for those items).
A full five stacks of Nephalem Valor is required, though, so just keep that in mind.
2.) since the chance for a bonus item to drop on MP10 is 100%, shouldn't that mean that any enemy that drops an item will drop 2? if the bonus item chance is 100%, no normal enemy should be able to drop only 1 item, right?
If you kill a monster while playing on MP10, and that monster makes its initial roll check to drop an item, it should have a 100% chance to drop a bonus item. So, yes, in that sense, the monster should drop at least two items. BUT, since the initial item a monster drops might just be a pile of gold, it's possible (with auto-pickup) that you may have just missed it. If you feel that something isn't working correctly, though, then please be sure to post in the Bug Report forum so our Quality Assurance team can investigate.
(Also, I saw this asked earlier, but the bonus item will always be a piece of gear, not a potion or gold or anything else.)
Magic Find does not have any impact on the drop rate for keys or organs.
Diablo III patch 1.0.5 is now live in the Americas. Check out the full patch notes below to learn about all the latest changes.
Important: Please note that you will not be prompted to download patch 1.0.5 until the patch is live in your home region. If you are logging in from a European or Asian client, you will need to wait for this patch to release in that region before it can be installed. Additionally, if your home region is the Americas, you will be unable to log into Europe or Asia using Global Play after patch 1.0.5 is live until those regions have also patched.

The latest client patch notes can be found here.
Visit our Bug Report forum for a list of known issues.
New System: Monster Power
Similar to the "Players X" command in Diablo II, Monster Power is a system designed to give players more control over how challenging enemies are in each difficulty. With this system, players can choose to increase the health and damage of monsters according to different "power levels" and in return they'll receive scaling bonuses to experience as well as boosts to Magic Find and Gold Find which will stack above the 300% cap. The option to increase Monster Power will be available to all players starting at level 1 in the Quest Selection window, and can be adjusted separately for Normal, Nightmare, Hell, and Inferno difficulties.
For more information on how to enable and use Monster Power, click here!
New Event: Infernal Machine
The Infernal Machine is a device that will allow level 60 players to battle "uber" versions of some of Sanctuary’s most nefarious bosses. While the rewards for defeating these bosses will be great, some assembly is required. Only the most powerful Nephalem can unlock the secrets to building the Infernal Machine, but once forged the device can be used to open portals to special encounters featuring not one, but two bosses which have been augmented from their original versions, both in terms of difficulty and appearance. Defeating each boss pair will provide players with extra items and gold, as well as a chance to find components for a new Legendary ring.
For more information on the Infernal Machine event, click here!

If you are experiencing technical issues with the patching process, connecting to Battle.net after installing the patch, or errors while playing a newly-patched game, please visit our support site or post in the Technical Support forum for assistance.
EDIT: SERVER IS NOW UP!
Looks like we are going to have to wait just a bit longer to get a crack at the Infernal Machine and other new features.
We're extending maintenance for the Americas region by 2 hours and now anticipate that all game services will be available by approximately 3:00 p.m. PDT.
The latest client patch notes can be found here.If you are experiencing technical issues with the patching process, please visit our support site for assistance.
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We will be performing scheduled maintenance for Diablo III starting tomorrow at 3:00 a.m. PDT in order to deploy patch 1.0.5. We anticipate that maintenance will conclude and that all services will be available by approximately 1:00 p.m. PDT.
Important: Please note that you will not be prompted to download patch 1.0.5 until the patch is live in your home region. If you are logging in from a European or Asian client, you will need to wait for this patch to release in that region before it can be installed. Additionally, if your home region is the Americas, you will be unable to log into Europe or Asia using Global Play after patch 1.0.5 is live until those regions have also patched.
Blizzard just posted their official blog and guide to the Inferno Machine.
Ready for a double dose of diabolical danger? In patch 1.0.5, level 60 players will be able to forge a cursed construct called the Infernal Machine, allowing them to battle "uber" versions of some of the most malevolent mischief-makers this side of New Tristram…in pairs. While the rewards for defeating these extra-bad bosses will be great, some assembly is required.
Read on to find out how to craft the Infernal Machine, where it can be used, and what epic rewards await those brave enough to unlock its secrets.
To craft the Infernal Machine, players will first need to collect four components from powerful Keywardens in each Act of Inferno:
(Each component will be considered "Bind on Account," which means they can be used by any character on your Diablo III license.)
Players will be able to encounter the Keywardens in any difficulty, but only in Inferno and with a full five stacks of Nephalem Valor will they have a chance to drop pieces of the Infernal Machine. While Monster Power is not required, each level will increase the drop rate of both the keys and the plans by 10%, all the way up to a guaranteed 100% drop chance at Monster Power 10.
After all the components have been collected, they can be assembled in town at the Blacksmith. Your Blacksmith will need to be level 10 in order to learn the Legendary plans, and he'll require 12,000 gold to forge the device in his furnaces.
Once crafted, the Infernal Machine will remain in your inventory until activated.
Once assembled, the powers of the Infernal Machine can only be unleashed in one location -- a cellar in New Tristram known simply as the Heretic's Abode. To activate the device, enter the cellar (located just behind Brother Malachi the Healer) and right-click the item in your inventory. This will summon an ominous red portal that will lead you to a demonic realm where you'll be pitted against a pair of Sanctuary's most nefarious villains.
In order to access the Heretic's Abode, players will need to set their quests to "Act I – Return to Tristram."
Activating the Infernal Machine will also destroy it, so to open another portal, you must craft the device anew. This process will include recollecting each of the three wardens' keys as well paying another 12,000 gold to the Blacksmith. (Don't worry about the plans -- once you've trained your Blacksmith, they will remain available in your crafting list for use at any time.)
Those brave enough to step through the Infernal Machine's ominous output will be transported to one of three randomly selected Realms of Pure Evil, where a predetermined pair of bosses awaits:
In the Realm of Discord, King Leoric and Maghda guard the Royal Crypts.
In the Realm of Chaos, Ghom and Rakanoth defend the Larder.
Finally, in the Realm of Turmoil, Siege Breaker and Zoltun Kulle protect the Edge of the Abyss.
In terms of difficulty, the encounters will be about as challenging as the Diablo fight in Inferno, and each "uber" boss will retain their full arsenal of base spells and abilities. Many of the abilities are more powerful, and certain bosses have even come up with new tricks to test those who dare to enter their domain.
If you happen to fall while battling one these Infernal foes, don't worry -- as long as you don't leave your game session, you can release and restart the encounter at any time by clicking on the very same portal you created. Similarly, even after both bosses have been slain, your portal will remain active in the Heretic's Abode until your game session has ended, which means that if you're out of inventory space, you're welcome to leave and return without losing your loot.
(Please note that you cannot be sent to the same Realm of Pure Evil twice in a single game session. This means that if you create or have access to four or more Infernal Machine devices, in order to use all of them, you'll need to start up a brand new game once you've opened up three portals.)
For successfully defeating a boss pair, players will be rewarded with extra items and gold. In addition, they will also have a chance to harvest demonic organs from each of their fallen foes, which can be used to create a Legendary item of unique power: the Hellfire Ring.
Similar to the wardens' keys, a full five stacks of Nephalem Valor will be required for the organ pieces to drop, and each level of Monster Power will increase their drop rate by 10%.

Each time you wish to craft a Hellfire Ring, you will need to present all three organ pieces
as well as 15,000 gold to the Jeweler.
Once all of the organs have been collected, they can be combined at the Jeweler using a new design available for purchase from Squirt the Peddler. This design will teach your level 10 Jeweler four variations of the ring: the Hellfire Ring of Intelligence, the Hellfire Ring of Strength, the Hellfire Ring of Dexterity, and the Hellfire Ring of Vitality. Depending on which variation you choose, your ring will be guaranteed to roll one primary stat with a set value range of 170–200.
In addition to the guaranteed primary stat, each ring will always have the following:
The Hellfire Ring will be considered Unique-Equipped, which means that players can only wear one at a time. Your followers will be able to equip the ring, however, and given the boost to experience and absence of a level requirement, the rings make excellent heirlooms to be passed down to each of your alts. If you no longer find the need for one of your rings, simply salvage it for materials at your local Blacksmith. So create one or create more -- the choice is up to you!