That's not quite right either, actually. Let me see if I can explain this.

When you have a 1 PPM effect (which is actually pretty hard to find these days, since, for instance, Mongoose is now thought to be more like 1.2 PPM, and most of the other procs have internal cooldowns), that means that, if all you do is autoattack, it will proc, on average, about once a minute. If you are using a 2.6 speed weapon which thus hits 23.1 times a minute, your chance of proccing on any given attack is 1/23.1 = 4.33% per hit. Hence, it will proc about once a minute.

Haste doesn't actually effect this; if you're a rogue, say, and have 30% increased attack speed via SnD such that your autoattack hits 30 times a minute, the proc rate per hit drops to 1/30 = 3.33% per hit, so it *still* procs, on average, once a minute. So regardless of what haste effects, passive, proc, or otherwise that occur, the proc chance adjusts dynamically, so my MH weapon generates about 1 PPM from autoattack.

However, what *does* effect this is instant attacks. As a rogue, I get a Sinister Strike once every 3 seconds on average. Regardless of what haste effects I may or may not have up, this procs at the rate determined by my base weapon speed. So if I'm using a 2.6 speed weapon, even if I'm hasted so my autoattacks are hitting 30 or 40 times a minute, my Sinister Strikes will still proc 4.33% of the time and thus give me an extra .85 procs in the average minute. Hence, if I have a 1 PPM enchant on my MH weapon, it will actually *proc* about 1.85 times a minute.

Also, some PPM effects work on both hands. If I'm wearing Madness of the Betrayer (thought to be 1 PPM), I will get about 1.85 procs per minute from my main hand, and another 1 PPM (based purely of autoattacks) from my OH. Hence, this 1 PPM effect will actually end up proccing about 2.85 PPM.

Now, the trick is, proccing 2.85 times per minute with a 10 second buff does not mean you'll have an average uptime of 28.5 seconds out of every 60; in practice, the procs tend to occur while other procs are happening, so the actual uptime is lower than this; a 10 second buff that procs 2.85 times a minute (on average) will end up with uptime of 38.5%, so will only be up about 23 seconds out of every 60.

To summarize: PPM effects are actually fairly sophisticated, and require a careful explanation of many issues to understand.

Reference for MathTeX formatting, slowly adding things in.

I've been doing quite a bit of research on this topic lately via other threads in EJ, WoWwiki, Allakhazam and the native World of Warcraft forums and was unable to find much information on the subject. Thus, I thought it would be appropriate to address on this thread. I was just curious as to how various spell combat events-- such as resistance, spell reflection (although this mechanic is only present in a few encounters) and absorption-- are integrated into the spell-combat tables, if they are.

My guess is that all the events which relate to mob mitigation are accounted for simultaneously with hit in the first roll, when determining whether or not the spell makes initial contact with its target. WoWwiki proposes that resistance is rolled separately after hit. However, with a series of tests, I have proven this cannot be the case and both events must be rolled simultaneously.Take a caster who has 50% hit (yes, theoretically impossible at the moment) and whose target has a 50% chance to resist spells for example. If Hit and and binary resistance were rolled separately there would still be a 25% chance for the player to successfully hit the target (.5 x .5 = .25). While, rolled on together on a single roll, there would be a 0% chance for the spell to make contact with the target (.5 + .5 = 1), a more theoretical result.

Subsequently, after determining that the spell has made contact with the target, the server rolls a second time to determine whether the spell will score a critical strike or result in a plain a hit, depending on your hit:crit ratio. Using a different example: if a players hit chance is 95%, the players crit chance is 40%, the chance for the boss to reflect a spell is 5% and the bosses effective resistance of 3%, when a spell is cast:

First Roll:
If the "die" roll result is 1-5 then the spell will miss the target
If the "die" roll result is 6-8 then the spell will be fully resisted
If the "die" roll result is 9-13 then the spell will be reflected back to the player

If the "die" roll result is 14-100 then the spell will successfully contact the target and the server will proceed to its second roll:

Second Roll:
If the "die" roll result is 1-40 then the spell will result in a critical hit
If the "die" roll result is 41-100 then the spell will result in a regular hit

Now, I'm still unsure about how non-binary spells and partial absorbs would be integrated into a simple combat event table like the one above, given that in a partial absorb or resist situation, the spell would not be completely mitigated and thus, it would not lower the effective chance to hit or crit. Please correct any mistakes if I am wrong.