Last night I went to give Diablo III another shot around games of Blood Bowl (my TMNT themed Nurgle team won two games in a new mini-league!) without really knowing what to expect. I knew broad strokes about the new systems from reading the patch notes and talking a bit with Randy but I didn't really know details. What monster power level should I set? Not knowing what it would do beyond make things harder and drop more stuff I didn't really know what to expect. Randy was saying he plays on MP5 and his gear seemed considerably better than mine so probably something lower, right?
I decided to try MP4, but my first attempt didn't work at all. It turns out Blizzard buried the ability to even use monster power in one of the option menus and you need to go turn it on outside of a game before you can change the setting. You can also only change the slider outside of a game (so no farming up a full stack of the Neph buff on MP0 and then powering up to MP10 for awesome loot) which seems reasonable enough. My second try worked, but MP4 was rougher than I wanted. Even with being very rusty I couldn't really die (force armour and teleport refreshing on damage are still awesome) in Act 1, but the monsters had stupid amounts of health and my disintegrate just wasn't doing enough damage. I also didn't realize MP0 was an option at the time so I thought I was moving the dial up 3 levels (from a base of MP1) when really I was going up 4 levels. On the plus side I did get an upgrade from the first elite pack I found on MP4.
Next up, MP2. This seemed a lot more reasonable and felt a lot like how I remember the game from launch. It felt like I was killing monsters at around the same speed I used to (with both my disintegrate build and a blizzard/hydra build) but the monsters were doing less damage (to the point of sometimes not proccing my teleport refresh) and were definitely dropping more stuff. Having the Neph buff apply to loot from resplendent chests and add a new stack was also nice! I found I couldn't really kill a treasure goblin with my disintegrate build on MP2 but could barely do it with blizzard/hydra. This makes me think MP2 is probably the top of my range with my current gear and a blizzard spec, that my disintegrate spec is terrible, and that maybe I should research some actual builds and see if I can find something even better.
But now that I played around with it a little I want to see some real details. What exactly is changing when you turn up the monster power dial. I found a couple nice charts on the Blizzard site but they only show the initial 1.0.5 launch numbers and not the tweaks that have happened since. The first thing those charts showed me was that monster power does apply to pre-inferno difficulties (a question Ike asked me in game yesterday). It works a little differently and the scaling isn't nearly as brutal (MP10 on normal is 4x monster health. MP10 on inferno is 34x monster health!) but you can definitely turn up the dials and level faster if you can mow through tougher dudes.
On inferno the scaling is more extreme and it also does three additional things. The first is the MP level determines the drop rate of keys and organs for the infernal machine event. It sounds like MP0 is 5% and every other MP level is 10% per level, so on MP10 you have guaranteed drops. The second thing is normal monsters that drop an item (apparently 30% chance) have a chance of dropping a second item. It doesn't seem like a big deal but it does mean you'll get more stuff when clearing trash packs. The last thing is the monsters in Act I and Act II are leveled up to level 63 if you're running any MP level above MP0. This means every monster has the same ilvl loot ratio so you can actually fight anywhere you want and get the same value stuff. It also means the monsters in AI and AII get a bigger bump by going from MP0 to MP1 than other monsters do because they get both the +50% health boost from the MP1 and get more base stats by leveling up from 61 to 63.
I couldn't find an updated chart anywhere consolidating all the patch changes so I went through the patch notes and built my own. Enjoy!
One thing that really jumps out at me is that monster health drastically outpaces the rest of the rows. So if you aren't just murdering regular dudes then you don't need to bump up the monster power, with a couple exceptions. Getting into MP1 is really worth it if you're fighting in AI or AII by bumping up the drops to the top of the curve. And if you're trying to farm infernal machine pieces then it can be worth ramping it up. There's only one guy who drops each key, and you need to stack your Neph buff up before you can get a drop off of him. So it can really be worth increasing the time it takes to kill that guy to bump up the key odds. (Also, the XP, MF, and GF rows are an addition so the gains aren't as big as they seem. MP2 isn't twice as good as MP1, it's 20% better. (1.5/1.25)) MP5 is 5x the odds of a key drop and only ~4x the health of the monsters compared to MP1, for example.
For people who may be curious (I certainly was!) it sounds like the system was tuned such that the old difficulty is about the same as MP2/MP3. I couldn't find specific details but I would guess for AI and AII that MP2 is about the same with the two boosts and for AIII and AIV that MP3 is about the same. I remember AIII being pretty rough but doable with my gear so I should be able to smash things on something like MP0 or MP1 now.
I figure it's probably in my best interest to farm drops/xp for a while to power up my gear a little and then shift to a higher MP level and go after infernal machine keys. So I think I may give MP1 a try tonight and see if it's too easy. On the plus side I already got a paragon level last night. Woo!