Here is what I can make out of defense stat based on the formula we got form
wangchengxy . The Attack fomula is as follow (Copy&Paste from
Saltin 's post, thus, will use the same terminology),
Attack = (panel attack * defense coefficient * weapon to armor coefficient * terrain work damage reduction panel value * buff effect I * (violent + threat) + buff effect II) * city wall coefficient From the, this
defense coefficient works as a discount factor that multiplies the incoming attack and makes the number smaller. So let's look into how this
defense coefficient is calculated. The formula is here,
Defense coefficient = (9 * panel defense * buff effect IV + 1850) / (28 * panel defense * buff effect 4 + 1850)Let's ignore the Buff IV and focus only on the
panel defense.
- When
panel defense is 0, the numerator and denominator are equal. That makes
defense coefficient = 1. Thus, the incoming damage is taken in full.
- As the value of
panel defense gets larger, the difference between numerator and denominator also become wider. This makes the value of
defense coefficient less than 1. Thus, the incoming damage is taken partially.
- The larger the
panel defense gets, the smaller
defense coefficient becomes and the less damage is taken.
So how big is the impact of panel defense on
defense coefficient and troop's survivability? Here is my little calculation on a spreadsheet. Terms and assumptions are explained below,
Def: panel defense
9*Def + 1850: numerator part of the defense coefficient equation
28*Def + 1850: denominator part of the defense coefficient equation
Defense Coefficient (%): defense coefficient, expressed in percentage. Calculated by numerator / denominator. Can be interpreted as a percentage of damage taken from an incoming attack.
Damage taken: Amount of damage taken assuming the incoming damage is 50.
Survivability: Assuming that your HP is 500, how many hits is required to kill you. Can be interpreted as how much damage you can sustain before you die.
Additional Survivability: How much more survivability you have for each amount of Def compared to Def = 0.
Notes:* Since this focuses on the impact of panel defense alone, I assume that there is no buff effect IV involved.
* Factors such as weapon to armor coefficient, terrain work damage reduction panel value, buff effect I, etc are treated as external factors, thus incorporated into incoming attack.
* Assume no city wall protection
* HP = 500 and Incoming damage = 50, are made up some numbers just for illustrating the impact. The choice of numbers is irrelevant since the impact of Def is expressed in percentage.
As you can see in the table, the additional survivability you get from an additional point of
panel defense is about 1%. But as the panel defense gets higher, the survivability increases at a slower rate (e.g. 1 def gives less than 1% additional survivability).
At
panel defense = 10, the troop takes 91.08% of incoming damage which is equivalent to 9.79% survivability.
If a general of this troop is equipped with...
+3 def item then
panel defense: 10 -> 13, survivability 10.98 -> 11.26. That is, survivability increases by 2.52%
+5 def item then panel defense: 10 -> 15, survivability 10.98 -> 11.44. That is, survivability increases by 4.16%
+7 def item then panel defense: 10 -> 17, survivability 10.98 -> 11.61. That is, survivability increases by 5.77%
In my opinion, the benefit from wearing +def items is quite disappointing. You can get your survivability up by 9%, 12%, and 15% with +HP items. These +HP items increase troop HP in percentage (even though it does not say so in the description).
In conclusion, this def stat is not entirely useless. It reduces the incoming damage so it has multiplicative effect with additional HP (i.e. makes it more difficult to reduce a fixed amount HP). However, its impact size is not that great (less than in EW6) and that make +Def items less competitive.
Disclaimer: This is based on my understanding about the given formula, thus, it can be wrong. I just want to share what I find.
