Estimating the Damage dealt by purely Auto Attack reliant ADC's

Coughaholic··2 votes·927 views

The passive damage from Blade of the Ruined King ( a percentage of a champions remaining health ) greatly convoluted the estimation of the time it takes an auto attack reliant champion to completely kill an idle opponent, ignoring health regeneration. Below is the method I have utilized so far, I do seek to make my method more robust and account for the time it takes to stack up a Guinsoos Rageblade during combat, among other things.

** 1) Assignment of Variables**

let the following be taken as definitions Z = Total health of the enemy champion X = Remaining health of the Enemy Champion Y = Missing health of the Enemy Champion h = The number of auto attacks executed a = The on hit flat damage dealt to the enemy as true damage b = The % max health damage dealt to the enemy as true damage c = The % Remaining health damage dealt to the enemy as true damage

Thus this is the equation for a single auto attack,

http://mathurl.com/h9e9d5q.png

This means that,

http://mathurl.com/gr7m8fu.png

** 2) Estimating The integral**

let y(n) = be the damage dealt by nth auto attack

thus y(1) = a + bZ + cZ y(2) = a + bZ + c(Z-y(1))

and in general,

http://mathurl.com/jerubg8.png

thus,

http://mathurl.com/zspjpse.png

** 3) Estimating h**

Now rather than treat h as one of a set of discrete values and have to evaluate the sum by hand, an approximation will be used.

http://mathurl.com/znvtfjm.png

Thus,

http://mathurl.com/zc63ego.png

Then we evaluate the integral of X over h finding,

http://mathurl.com/gttqc94.png

Please note, this is a transcendental Equation, however if the Lambert W function is utilized h can be found to be.

http://mathurl.com/zro3fqc.png

** 4) Hits to Kill a Damaged Target **

Please note that, although we have a closed form value for h, actually evaluating W requires an iterative process.

Similarly, using the same process we can find the number of hits it would take to fell a damaged enemy.

First we find the hit equivalent for their current health yielding a slightly more complicated equation.

http://mathurl.com/hmhp57w.png

where A is the hit equivalent to the amount of damage taken by a given champion.

After solving for A and h numerically, the number of hits to kill a damaged enemy, H, becomes

http://mathurl.com/zz7ryvn.png

** 5) Time Taken to Kill a Target **

Let S = Attack speed of the ADC T = Time required to Kill the Target

http://mathurl.com/hh6bwwa.png

2 Comments

My eeeeel2 votes

Your equation lacks attack speed and critical strike portion, which are pretty simple to add.

Coughaholic1 votes

For the sake of readability of the formula, I opted to avoid using Crit, armor, Mr, or any other convoluting factor in these expressions. Adding them requires the variables a,b,c to be broken down into their physical and magic based components then be adjusted to a true damage equivalent by accounting for armor and mr.

For accounting for Crit, I plan on using the expectation value of the damage for each hit.

In effect the goal of this was to work out the most straight forward way to estimate the number of hits to kill an enemy for a build optimizer I am planning on coding. Because not all champions react the same way to critical strike chance and other stats, I opted to calculate the champions damage profile in relation to the variables a, b, and c with a given build.

I will plug in a time function to demonstrate better how how long it takes to kill an enemy as this is usually more valuable than just the number of hits to kill an enemy.

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