There's a new blog post up on the official Diablo III website, in which the team at Blizzard Entertainment shares the mechanics and design philosophy driving their new "monster power" feature that's headed to the action RPG in its v1.0.5 patch.
Monster Power will be disabled by default, so before you can make any adjustments, you'll first need to enable the system. To do so, open up the Game Menu, click the Options button, and then click the Gameplay tab. You'll see the Enable Monster Power Selection box on the right side of the screen -- check that, and then click Accept.
Once enabled, the option to set Monster Power will appear in the lower portion of the Quest Selection window next to the Difficulty drop-down menu. You can choose from Monster Power 1 (MP1) all the way up to Monster Power 10 (MP10), or you can opt for No Monster Power (the default setting) to play the "normal" challenge level for your chosen difficulty. Monster Power can be adjusted separately for each hero and difficulty, and can be changed at any time through the Quest Selection interface.
At the launch of patch 1.0.5, Monster Power will be available in both solo and private multiplayer games. Whenever you join a private multiplayer game, your hero will temporarily adopt the Monster Power level set by the party leader, and it will return to the previous setting you selected as soon as you leave the group. (Please note that you will not be able to adjust Monster Power in Public Games at the feature's launch, though we're looking into the possibility of adding that ability in the future.)
Monster Damage vs. Monster Health
Since the goal of this system isn’t to make the game ultra-hard, with each Monster Power level there's a heavy emphasis on increased monster health rather than monster damage. This is because, in general, it's more fun to find ways to maximize your damage than it is to be forced into taking every available form of damage mitigation. We also didn't want to create situations where "hard to beat" could become "impossible to beat" because players couldn't survive long enough to make any progress. In our testing, we found that while scaling up monster damage certainly made some fights more challenging, it did so in unfair ways…and also made it quite easy for heroes to be one-shot. Increasing the health of monsters, on the other hand, allowed the game to scale up in difficulty more naturally and in a way that still felt manageable.
By now, some players have reached a point where they can kill monsters so fast that even Inferno provides almost no challenge, and enemies die as soon as they appear on the screen. For these players, the bottleneck for efficient farming is actually the speed at which they can traverse the map rather than how well they can dispense with enemies.
This is where Monster Power can shine. Players who can clear every Act of Inferno without much problem can increase their Monster Power for a more enjoyable and interesting challenge -- as well as better rewards -- and keep pushing their limits all the way up to Monster Power 10. Will some players be able to kill Diablo on Monster Power 10 as soon as 1.0.5 goes live? Absolutely. Will that be the most efficient Monster Power level at which to farm items? For most, probably not. Monster Power allows each individual decide what that "sweet spot" is for them.