STAT-DAMAGE-KEYWORD SYSTEM
The KDV SYSTEM "calculates" a models points costs based on weighted conjunctions of all utilizable information given on its warscroll.
MODEL COSTS
Calculate the costs of each and every single model seperately as follows:
(Stat-Costs + Damage-Costs + Keyword-Costs) * PVS Modifier / 4
STAT - COSTS
180 / Save * Wounds + 2 * Move - (20 - 2 * Bravery)
DAMAGE - COSTS
(Range / 1.5 + (7 - To Hit) + (7 - To Wound) + 3 * Rend + 4 * Damage) * Attacks
Add 1 weapon with the Arcane Bolt stats for each spell a Wizard can cast each turn
KEYWORD - COSTS
(Stat-Costs + Damage-Costs) * X
X = 0.0 if 0 of the following Keywords can be found on the Warscroll: Hero | Monster | War Machine | Wizard | Priest
X = 0.2 if 1 of the following Keywords can be found on the Warscroll: Hero | Monster | War Machine | Wizard | Priest
X = 0.3 if 2 of the following Keywords can be found on the Warscroll: Hero | Monster | War Machine | Wizard | Priest
X = 0.4 if 3 or more of the following Keywords can be found: Hero | Monster | War Machine | Wizard | Priest
SPECIAL CASES
Count save "-" as 7 Count bravery "-" as 0
Count "*" as the highest possible value
Count "D6" as 3,5 and "D3" as 2
Count Mortal Wounds as follows:
Damage = average number of wounds caused
Rend = 4, To Hit & To Wound = 0
Count "Reroll all failed X" as X - 1
Count "Regenerate all wounds on 2 + once" as Save - 1
Count "Heal D3 or more wounds in the hero phase" as Save - 1
Count "Halve any wounds or mortal wounds inflicted" as Save -1
Count "Ignore each wound or mortal wound on 5+" as Save - 0.5
Count "ignore each mortal wound on 5+" as Save - 0,5
Count "Reroll all failed saves of 1 and 2" as Save - 0.75
Count "Add 2 to all saves in the Shootingphase" as Save - 0.75
Count all upgrades for models that are not weapons or permanent alltime stat buffs as free
Count "number of attacks = models in range" as 1 Attack per 2" range, rounding up
Count "Reroll all ones" as +/- 0.5 of the value
Count "Your opponent must substract 1 from hit rolls" as Save - 0.25
Count all shield, armour and ability Save bonuses not seperately specified as Save - 0.5
Count "Heal 1 wound in the Hero Phase" as Save - 0.5
Count "Heal D3 wounds on 4+" as Save - 0.5
Count "Heal D3 wounds if models had been slain" as Save - 0.5
Count "Heal X wounds if Y happened" as Save - 0.5
Count Engineer bonuses as always active on Warmachines
...
Interaction Model (PVS)
The interactions models (by Andreas B.) says that a units ability to do damage interacts with its ability to sustain damage. This means a unit that is more likely to die before it can deliver its damage is less effective than a unit that can sustain more damage and that the ability to do damage in its effectiveness depends directly on its ability to sustain damage.I think so far this is common sense among all players. Statistically this means you should/must use a interactions model. This looks simplified like that (you can find the complete model on Wikipedia. for gaming purpose I assume β=0 y=x1*x2
Points value of a unit is y= offensive value * defensive value
The offensive value of a model in AoS can be calculated pretty much straight forward. You must calculate the expectancy value(see Wikipedia for Expectancy-value theory)
The expectancy value of an attack is:
attacks * chance to hit * chance to wound * damage*transformed rend
(dice need to be transformed to their expectancy values (d3=2, d6=3,5))
Calculating rend into is more difficult. The relative value of rend depends on the models you are fighting against. If your model has rend -1 and your opponent only hat units with no armor save, the rend value will bring you no benefit. There for some estimations and assumptions are necessary and must be debated to find the exact values. Every rend value must be transformed in an multiplier. My suggestions are:
rend 0 = 1
rend -1 = 1,5
rend -2 = 1,8
rend -3 = 2,0
So an weapon with rend -3 will double the offensive value compared to a weapon with no rend. The difference between rend -1 and rend -2 should be greater than that between rend -2 and rend -3. Because rend -3 will be of no further use against armor save 6+ or 5+ than rend -2.The next thing is to consider in movement and range. Every attack of a model possess a threat range that is based on the movement of that and the range of that weapon.Threat Range
For melee weapons this is:
movement + average assault range+ range of weapon
For ranged weapons this is:
movement + range of weapon
This brings us to:
offensive value of each weapon is threat range*expectancy value of an attack*transformed rend value
To get the offensive value of a model you must add up the offensive values of all its weapons.The defensive value of a model only depends on its wounds, armor save and bravery.defensive value = wounds/chance to bypass save*transformed bravery value an example:a model with wound 1 an armor save 5+ would be 1/4/6 this 6/4 this is 1,5. Armor save 5+ means you need to achieve 1,5 damage so that the model will lose 1 wound.Transformed bravery value:this is the biggest problem. this is difficult to be calculated by an expectancy value.The value of the bravery of a model depends on the ability of the opponent to deal as much damage as possible to a unit of such models. Furthermore there are bravery values for models, that don't need them like solo models that can't form unit and will never do a bravery check and which cant lend their bravery to other units.what I used is the following
Bravery 4 multiply by 0,55
Bravery 5 multiply by0,75
Bravery6 multiply by0,90
Bravery7 multiply by1,00
Bravery8 multiply by1,05
Bravery9 multiply by1,10
Bravery10 multiply by1,15
So in the example above a model with 1 wound, armor save 5+ and bravery 7 would have a defensive value of 1,5*1=1 So we have calculated a offensive value and a defensive value for any given model. Special abilities are not accounted.
Points value = offensive value * defensive valueThe last step is modeling the formula, so that the points value don't explode.
Points value = offensive value 1/2* defensive value 1/2 (1/2is the same as the square root)