Blade Flurry

Blade Flurry is a channeling melee attack. While channeling, Blade Flurry repeatedly attacks a random enemy in front of the player, also damaging enemies nearby the original target. When released, it will unleash an extra number of attacks equal to the stage reached.

Skill functions and interactions

 * Stages: Each attack, while channeling, applies a single stage that grants 20% more damage, up to 120% more damage total at 6th stage. Each stage will also add an extra attack to the release of Blade Flurry.
 * Dual wielding: The skill alternates between the main hand and the offhand for each hit.
 * Area of effect: Modifiers to area, such as and, affect both the radius of the main hit and the radius of the explosion caused by it.
 * Trigger supports: While both and  can support Blade Flurry independently, they won't work in tandem; neither will trigger.
 * : Blade Flurry (and all channelled skills) cannot be supported by Multistrike.

DPS Calculation
Blade Flurry's tooltip DPS is not accurate, because it shows Average Damage (ignoring Attack Speed) and doesn't account for stage bonus. Here is how to calculate the actual DPS: $DamagePerSecond = Base \times 1.6 \times 2 \times StageMult$

where Base is the base damage given by gem level, and StageMult ranges from 1.1 to 1.85 (see table in Derivation) depending on which stage level was reached before releasing. This formula also assumes the player's return strike(s) can hit an enemy; remove the 2 in the middle to approximate what happens when the return strikes don't hit an enemy.

For example, at gem level 20, with "perfect channeling," as of patch 2.6: $DamagePerSecond = 0.5464 \times 1.6 \times 2 \times 1.85 = 3.33888$

or 334% weapon damage per second. Note that the DPS will be slightly lower in practice because players cannot reach perfect channeling, only get very close.

Importantly, these assumptions are based on a theory vs practice test that indicates that Stage bonus is not applied when reaching that stage (aka, first hit doesn't get 20% more damage; second hit gets 20% more damage, third hit gets 40% more damage, and so on) while return strikes get the full stage bonus as reached (aka, one hit and one return strike means the return strike has 20% more damage, two hits and two return strikes mean the return strikes all have 40% more damage, and so on). This can be backed into based on Zrevnur's DPS test in a patch where Blade Flurry had 66.4% of base damage at level 20 and a 65% more Attack Speed multiplier:

"Blade Flurry vs Reave: 2.86x damage vs single target"

((.664*1.65*2.2)+(.664*1.65*1.5))/1.38 = 2.9375, or 2.94x, which is approximately as much as Zrevnur's test, with some adjustment for nonperfect channeling, rounding of time-to-kill, weapon damage variance, etc.

We can begin with the most basic formulation, which is damage without channeling bonuses or return strikes. Let $b$ represent base damage multiplier and $a$ represent attack speed modifier as listed on gem description. Then, $dps = b \times (1+a)$

and we can add another copy of the same equation for the return strikes: $dps = b \times (1+a) + b \times (1+a)$

Now, we have to analyze stage bonus. We begin with the 6-stage case, where the return strikes will have the full 20% * 6 = 120% stage bonus: $dps = b \times (1+a) + b \times (1+a) \times (1+1.2)$

Then, for the build-up strikes, we have the average of strikes. We know strikes 1 through 6 will have stage bonus of n-1, as they will have the previous stage's bonus. This means that the average bonus of 0, 20, 40, 60, 80, and 100 will be 50, or, $1+0.5$. We get: $dps = b \times (1+a) \times (1+0.5) + b \times (1+a) \times (1+1.2)$

Now, as the buildup and return strikes have common factor of b(1+a), we can use distributive property to extract it in the manner of (xc + xd) = x(c+d) $dps = (b \times (1+a)) \times ((1+0.5)+(1+1.2))$

Now, we know that we essentially started out with "x+x" which is more intuitively accepted as "2x" - the common base is now found in the 1s on the right side of the equation. Instead of ${{1+0.5}+{1+1.2}}$ we can average this out to represent "average buildup and return strikes' damage bonus", then have a more intuitive "2x for twice the strikes" on the outside: $allhitsStage = 2 \times {(1+0.5)+(1+1.2) \over 2}$ $allhitsStage = 2 \times {3.7 \over 2}$ $allhitsStage = 2 \times 1.85$

Finding averages for buildup strikes for 1 through 5 stages is left as an exercise for the reader (for those who can't imagine the intuitive linear graph for this, you may have to look at all sets {0}, {0, 20}, {0, 20, 40}, {0, 20, 40, 60,} and {0, 20, 40, 60, 80}) This means stage bonus can be as follows, when we remove the 2 from $$ to look at average stage bonus instead of stage bonus and twice-the-hits bonus: $averageStage at 6 stages = {(1+0.5)+(1+1.2) \over 2}$ $averageStage at 5 stages = {(1+0.4)+(1+1.0) \over 2}$ $averageStage at 4 stages = {(1+0.3)+(1+0.8) \over 2}$ $averageStage at 3 stages = {(1+0.2)+(1+0.6) \over 2}$ $averageStage at 2 stages = {(1+0.1)+(1+0.4) \over 2}$ $averageStage at 1 stage = {(1+0.0)+(1+0.2) \over 2}$ for the following "average stage bonus when combining buildup and return strikes" table:

Now, returning to $$, we can use $$ to simplify: $dps = (b \times (1+a)) \times 2 \times (StageMultiplier)$ where StageMultiplier selects from $$ through $$, as a replacement for 1.85 in the 6-stages example. Moreover, for all levels, the attack speed bonus is 60% more, so dps will always be: $dps = b \times 1.6 \times 2 \times (StageMultiplier)$

Version history

 * Now deals base damage equal to, and has an added damage effectiveness of, 32% at gem level 1 (from 45%), up to 45% at gem level 20 (from 56%).
 * Now adds 14 to 20 physical damage to attacks at gem level 1, up to 75 to 113 at gem level 20.
 * Now has 29% larger target-acquiring radius while channelling, and 47% larger target-acquiring radius after channelling ends.
 * Now has an attack speed multiplier of 160% (rather than 60% more attack speed).


 * Damage reduced by 18% at level 1 of the gem, scaling to a 15% reduction at level 20 of the gem.
 * Radius has gained 2 units on all of its ranges. (The damage area has increased from 12 to 14 units, the channelling targeting area has increased from 15 to 17 units and the release targeting area has increased from 17 to 19 units.)
 * No longer gain increased area of effect radius.


 * Blade Flurry's "More attack speed" modifier has been reduced from 65% more to 60% more attack speed at all levels. Blade Flurry's targeting range has been reduced by 16.6%, and the damage radius of slashes has been reduced by 14.2%.


 * Added new Dexterity/Intelligence skill - Blade Flurry: Repeatedly strike at enemies in a circle in front of you while channelling, dealing damage to and around the struck enemy. The damage is continually boosted while channelling. You unleash an additional strike for each stage reached once the channelling ends. Requires a Dagger, Claw or One-Handed Sword.
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