Before we get too worried about the Sinister Strike formula, it is important to understand the basic damage formula.
- All of the following formula will have to be done twice, using minimum weapon damage once, and maximum weapon damage in order to determine the damage range. Alternatively you could use the average between the two to determine your average Sinister Strike damage.
This is the basic "White Attack" formula, which is the basis for the Sinister Strike formula.
(Attack Power / 14) * Weapon Speed + Weapon Damage = Damage
(Comment: I think it should be (Attack Power / 14) / Weapon Speed + Weapon Damage = Damage )
The formula will be shown using Sinister Strike Rank 10.
You'll notice that the "Weapon Speed" is substituted by "Normalized Weapon Speed" because we're dealing with an instant attack.
Normalized weapon speeds are as follows.
- Dagger: 1.7
- 1H Melee: 2.4
- 2H Melee: 3.3
In most cases, you'll be dealing with a 1H melee weapon.
(Attack Power / 14) * Normalized Weapon Speed + Weapon Damage + 98 = Damage
Notice the +98 damage added by Sinister Strike.
We mustn't forget that there are three Rogue talents that affect the amount of damage done by Sinister Strike.
With the full 5 talent points, Lethality "Increases the critical strike damage bonus of your Sinister Strike, Gouge, Backstab, Ghostly Strike, Mutilate, Shiv and Hemorrhage ability by 30%."
[(Attack Power / 14) * Normalized Weapon Speed + Weapon Damage + 98] * 2.3 = Damage
The critical hit multiplier gains the additional 30%(.3 in decimal) bonus from lethality.
With the full 3 talent points, Aggression "Increases the damage of your Sinister Strike and Eviscerate abilities by 6%."
[(Attack Power / 14) * Normalized Weapon Speed + Weapon Damage + 98] * 1.06 = Damage
The Sinister Strike damage is now multiplied by 106%(1.06 in decimal) to add in the bonus from Aggression.
Surprise Attacks "Your finishing moves can no longer be dodged, and the damage dealt by your Sinister Strike, Backstab, Shiv and Gouge abilities is increased by 10%."
[(Attack Power / 14) * Normalized Weapon Speed + Weapon Damage + 98] * 1.1 = Damage
The Sinister Strike damage is now multiplied by 110%(1.1 in decimal) to add in the bonus from Surprise Attacks.
Lethality, Aggression & Surprise Attacks
[([(Attack Power / 14) * Normalized Weapon Speed + Weapon Damage + 98] * 1.06) * 1.1] * 2.3 = Damage
It is important to remember that Blizzard "stacks" their percentages, instead of simply adding them to each other.