[Daldaen]

Melee Damage

Brohg writes the following description of melee damage recieved from mobs: "Mob damage is two parts, DB (Damage Base/Bonus or Fixed Damage /Vig), and (1-20)*DI, which is Damage Interval. You can see this by parsing, that there are 20 discrete amounts of damage any mob can deal on a successful hit. It's not quite /random 1 20, because AC makes a big huge difference in how many low hits you have, but you still have the whole range.
If a mob has a damage base of 200, and a damage interval of 20, then (once they hit you) they'll deal either 220 damage, or 240, 260... etc ... 580, or 600 damage."

"High AC (from gear /Vig) reduces the damage taken from the (1-20)*DI portion a lot, making many more low #*DI than high."

So all melee damage has two parts, one wich is random and affected by the AC on your gear, and one part that is never modified by AC. The Shielding effect in particular is extra interesting heresince Shielding affects only the Fixed Damage (and is the only thing that affects it), not the random Damage Interval.


Armor Class

Armor Class is what decides how much damage you take and how often you take damage. It mitigates damage and it makes the mob miss it's attacks against you. The first part of the AC is "mitigation AC" wich is calculated from the worn AC you gain from your gear. Taraddar writes: "Your "mitigation" ac comes from the AC on your gear and is what effects the distribution you get in the 1-20 portion of attacks. Higher ac gets more lower hits etc."

This means that the gear you wear decides how much of the random part ie Damage Interval (as described above) of the damage coming your way actually hits you.

The other part of AC is the "avoidance AC" wich is defined by your Defense Skill and your AGI stat. Taraddar writes: "Normally your defense skill and agility contribute to your "avoidance" ac and increase your chance of being missed. AC from gear doesn't effect this at all."


Attack

Attack, like AC, is also composed of two parts. One is based on your Strength and wielded weapon to decided how hard you hit the mob when you connect. Let's call this Power. Brohg writes: The Power part of Attack is how hard you hit, when you hit. No amount of power will raise your max hit, but those who are familiar with the (1-20)*DI nature of Everquest damage will understand that shifting your average hits higher on the 1-20 scale will lead to much more overall damage. This is what Power does. Power is modified by Offense skill, Strength score, and +ATK mods on items. In combat, Power is opposed by the target's Mitigation.

The other part of Attack decides how often you hit. This is based on your weapon skills. We can also safely assume that your Offense skill is also one part of the calculation. Again, Brohg teaches us: "Displayed "Attack" is Accuracy+Power. Accuracy is how likely one is to hit one's target, and in combat is compared to the Avoidance part of AC (more on that later). Accuracy comes from two sources, Weapon Skills and +Accuracy mods on items."

Is a solid description of how EQ mechanics work... But it doesn't have an exact ATK formula. Just what factors in, no numbers.