The Armor Effect (AE) depends on the difference of Effective Damage Rating(EffDR) and Effective Armor Rating (EffAR):
- AE = 2(EffDR - EffAR)/40
Effective Damage Rating
The Effective Damage Rating (EffDR) is a simple sum of the Base Damage Rating (BaseDR) and any Damage Rating bonuses (DRBonus).
- EffDR = BaseDR + DRBonus
For damage from spells and caster weapons (Staves, Wands, etc), the BaseDR is proportional to the attacker's level.
- BaseDRcaster = 3 × Level
For "weaponry" damage (martial weapons and pets - those that have an attribute line for it), the BaseDR depends on the attacker's rank in the respective attribute of the "weapon".
- BaseDRnoncaster = 5 × Rank
If the Rank of the linked attribute is greater than a threshold1 of Level/2+2, then there is a DRBonus of - 3 × [Rank - (Level/2+2)] (negative bonus), serving as a diminishing return. The square bracket term in this case rounds up (towards zero). This threshold only applies to "weaponry" damage, which results in a DRBonus of zero for non-critical hit attacks from spells and spellcasting weapons.
Expressed differently, the DR for non-caster damage is:
- DRnoncaster = 5 × Rank; if Rank <= Threshold
- DRnoncaster = 5 × Threshold + 2 × (Rank-Threshold); if Rank > Threshold
- Threshold1 = Level /2 + 2
For traps, Damage Rating is same as for spells and caster weapons: 3 x Level.
For a detailed chart showing damage rating at each character level/rank, see Damage Rating progression.
Critical hits grant a DRBonus of 20.
1 The equation for the Threshold has only been confirmed for levels 1,8,11,14~16, and 18~20. The equation is interpolated to cover levels 2-7, 9, 10, 12, 13, and 17, and may not be accurate at those levels.
The Effective Armor Rating depends on the Base Armor Rating (BaseAR), AR Shifter (ARShift), and Net Armor Penetration (NAP).
- EffAR = BaseAR × (1 - NAP) + ARShift
Each attack randomly hits one of the various body locations. The probablity of hitting each location is generally believed to be proportional to the relative armor costs for the same level of armor. If that were true, the probablities would be:
- Chest - 3/8
- Legs - 2/8
- Head - 1/8
- Hands - 1/8
- Feet - 1/8
However, it is also believed that certain attack skills and spells have a bias towards certain body parts, so they are more likely to hit them. Relative positioning of the attacker and target may also affect which part is more likely to be hit.
The Armor Rating of the piece corresponding to the location attacked is used as the BaseAR, while any bonuses on that armor contributes to ARShift. Certain armor are described as having a negative bonus of Holy Damage you receive is increased by 5, which function regardless of hit location and stacking.
Primary and secondary weapons, as well as skills, may also modify the armor value. They are added to the ARShift regardless of which body location was hit.
Armor penetration can come from the Warrior's Strength attribute, weapon upgrades, or skill properties. Some of them simply have x% armor penetration, whereas others provide +y% armor penetration. Pick the highest x (if none, use 0), and add all the y's to it to obtain the net armor penetration (NAP). Note that NAP is a real number between 0 and 1; remember to divide percentage values by 100 (20% → 0.2, etc.).