The effect of "Mitigation AC"
 

So I'm coming from a theorycrafting view from World of WowCraft. You add armor, you get hit for less. Boss hits for 1000, your mitigation is 50%, boss now hits for 500. That doesn't seem to be the case here. Here it seems like a Mob has a set DI20 table to pull numbers from, and AC will influence how often you pull hits from one side of the table versus the other. Am I right in my observation there?

Also, it seems like your avoidance numbers are set in stone, without diminishing returns. In WowCraft when you're fighting a boss, they have enhanced numbers and your avoidance counts for less. Here it seems you just do "Dodge_Skill/400" and that's your dodge chance, period. It doesn't leave a lot of room for increasing your avoidance. Well, it leaves zero room. But this is a precursor to more complicated systems. Anyway, am I also correct here? You have your 210/400 = 5.25% dodge chance, period? Level 50 Warrior tanking a level 53 Cazic? 5.25% dodge. Same guy tanking Emperor Crush? 5.25% dodge. Really the only way to increase avoidance seems to be through agility, and it doesn't do an exceptional amount, and then it's capped at 250.

first part, as your AC increases, mobs start hitting you for less average damage. get to 900 AC, and you will see hill giants hitting you for the minimum, 21, a LOT.

2nd, yeah...flat rates as far as I can tell.


There's a reason everybody goes HP/AC

In fact there's a post from Rogean that says:

So your chance to be hit is based off of your avoidance, which implies a hard number.

This has helped me as a starting point

http://www.eqemulator.org/forums/showthread.php?t=40543

I've gone through that and the many other things that are pointed to in the wiki. It's just wrapping my head around the part where they use static numbers.

I may just be horribly incorrect, but assuming NPCs follow the hit = OffenseSkill + 7 + WeaponSkill, then 29 AGI = ~1% avoidance up to cap. Starting from the human base of 75 AGI, that's just over 6̶%̶ 3% avoidance. 20 AGI also 1 Mitigation AC. I'm still working on exactly how valuable AGI can be in that regard.

AC is good at the lowest levels or when a mob is much lower level than yourself. Basically anytime the content is trivial, AC is good.

World of Warcraft came from this world, and the guild leaders blizzard recruited when making the game took the stats that didn't do much and made them useful.

The usual disclaimer applies here: We're all talking about an uncertain subject. The true effect of abilities and statistics on P1999 has seen a lot of debate here over the years. EQ-Emulator is separate from EQ-Live, and at this point P1999 has become fairly distinct from EQ-Emulator. For the sake of having a discussion--it's useless to sit around saying, "well, we don't know"--I'll assume things work here basically similar to how these factors worked in the original game in-era. As a reader just remember it all comes with an *asterisk.

Mitigation and avoidance AC are different statistics that happen to be displayed as a composite score together. There is a 1-20 roll ("Damage Interval," or DI) that determines damage taken. Mitigation AC (armor gained from equipment or AC buffs) works against that roll by weighting it lower, provided monster attack values aren't so high as to make any obtainable AC ineffective. However, there is also a fixed damage bonus ("DB") portion of incoming damage, effectively the monster's minimum hit, that cannot be reduced by armor or other means. Avoidance is something of a mixed bag. Skill-based avoidance--Dodge, Parry, Riposte (and Block, I believe)--are fixed values that depend solely on the player character's level in those respective abilities. However, a monster's raw chance to MISS is affected by "avoidance AC" such as AC gained from agility or defense skill. This type of AC shouldn't have much or any impact on mitigation. Character level plays a role in both as well as is plainly obvious from simple observation. A level 40 Cleric who never bothered to train defense takes fewer, and lower, hits in melee on P1999 than a level 15 Warrior who maxed out defense for his level and hence has it higher than the above Cleric.

In actual practice, in-game it is much easier and more effective as a tank to gear for health and mitigation and accept what avoidance/agility you get than attempting to gear specifically for agility. The few players who attempt to do the latter tend to have a tough time of it and typically show poor results for the effort. Available gearing doesn't really support that type of setup very well. Theorycraft aside, you have to wear the equipment that exists and for plate classes in this game it heavily favors hitpoints and raw armor/mitigation.

-----------------------------------------------------

What you gear for as a tank depends on what you're mainly doing. Hit Points are and will always be king when acting as main tanks for most raids because what matters most in a Complete Heal chain is minimum time to death, not average. Being able to definitely survive one more max-hit round is far more useful than usually-but-not-always surviving a couple additional rounds. Outside that there's a lot more wiggle room. I mostly duo with the wife and maybe an additional friend or two; she plays a Shaman. I receive a lot of Torpor and very rarely have a Cleric around for Complete Heals. Hence raising my own maximum health does very little for me--Torpor will heal its 1200 whether I have 4500 health or 4000--so I'm much better off raising my armor as much as I can.

Danth

Great post, Danth.
Nitpicking here, but the minimum hit would be DB+(DI x 1).

Well if I go through with pushing numbers when I finally figure out exactly how the DI20 rolls can work in a spreadsheet, I'll be using Cazic Thule's known DB=200 and DI=20. I'm looking at the attack.cpp from the base eqemu as at least some kind of starting point. I'm sure it's fairly pointless because, as Danth pointed out, gearing for HP/Armor is the way to go, but I'm having a lot of down time when I do have to go in to work these days and it keeps my brain occupied.