Blizzard just posted a pretty well sized blog post about the inner workings of Monster Power levels.
Originally Posted by Blue Tracker / Official Forums)(
The option to adjust Monster Power will be available to all players starting at level 1 through the Quest Selection window, and can be adjusted separately for Normal, Nightmare, Hell, and Inferno difficulties. Here's how the system works....
Setting Your Monster Power Level
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.)
More Guts, More Glory
Starting at MP1, each level of Monster Power will increase monster damage and health by a scaling amount depending on difficulty. To reward your audacity, your hero will receive a scaling bonus to experience, Magic Find, and Gold Find (which will stack above the 300% cap).
For Normal, Nightmare, and Hell, the bonuses look like this:
In Inferno, in addition to increased experience, Magic Find, and Gold Find, whenever a monster dies and drops an item normally (whether it be gold, a potion, or a piece of gear), the monster also has a chance to drop an additional bonus item. The chance to drop a bonus item will scale up with each MP level as detailed in the table below.
In Inferno at Monster Power 1 or greater, monsters in every Act will also be bumped up to level 63 and share the same high-end item drop rates. This means that no matter which act you're progressing through, the monsters in that act will all have the same shot at dropping items level 61-63, including crafting recipes, Legendary items, and set items.
While monsters in Inferno will all be level 63 at MP 1 through MP 10, their skills, abilities, and attributes will still vary from act to act. This means that certain Acts or Chapters may still be more difficult for you than others based on what monsters and Elite packs appear in each, but -- since the rewards will be identical across the entire difficulty -- where you choose to play is ultimately up to you and your personal play style.
The Method Behind the Monsters
Now that we've explained the mechanics, let's delve a bit deeper into the design philosophy. The intent of Monster Power is not necessarily to make the game "unbeatable," but to provide better ways for players to measure their progress as they become more powerful. We've designed the system around this idea, with two primary areas of focus:
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. 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.
The Power Is Yours
In Diablo III, your character's power can grow by multiple orders of magnitude, but up until now there hasn't been a way for you to truly put that potency to the test. The Monster Power system provides a new outlet for high-powered heroes to truly see how far they've come and tangibly experience just how epic the gear they've collected is.
Different players want different levels of challenge, and with Monster Power you'll be able to determine what the right level of challenge is for you. Whether you're in it for the guts, the glory, or simply the goodies, we're excited to offer players the opportunity to face the forces of evil on their own (possibly slightly insane) terms.