Blade Fury [is] known to trigger a wide range of special effects:
So what changed in 1.10 to make Blade Fury a serious contender? Just two things: weapon damage was added to Blade Fury's token built-in damage, and Blade Fury was changed from an ITD attack to one that relies on your AR to hit.
This granted Blade Fury one of the most unique advantages in the game: the power to transform any melee weapon into a rapid-fire ranged weapon, requiring no ammunition and only minor mana costs. Compared to this, Blade Fury's apparent drawbacks became trivial or even beneficial:
First, let's look at what Blade Fury actually does in Patch 1.10:
Blade Fury acts in every respect like a ranged weapon. This means that its Crushing Blow damage is half that of a melee weapon...
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Blade Fury's 25% reduction in your weapon's total damage works exactly like Strafe and Multiple Shot. It has the same effect on both physical damage and elemental weapon damage. It does not, however, reduce the duration of poison, chill, or freeze effects.
With most attack skills in Diablo, maximizing your damage is a matter of investing skill points in your main spell and its synergies, and/or using the biggest, fastest weapon you can acquire along with boosting your strength and/or dexterity. Blade Fury breaks these rules in several ways, penalizing many of the most powerful weapons and revitalizing some of the most obscure. In addition, there are a few choice skills and special effects that work especially well with Blade Fury.
Venom: At level-20, Venom does around 435 poison damage over 0.4 seconds, a damage rate of about 1087 per second. This is reduced to 815 dmg/sec when used with Blade Fury. When spammed, Blade Fury does continuous poison damage, blocking the target's life regeneration. However, Venom poison wears off very quickly and its duration cannot be extended by other poison sources, making additional poison damage items useless. Venom damage can be boosted +25% by Trang-Oul's Claws bracers and +25-50% by Bramble rune word armor.
Claw Mastery: (CM) At level-20, Claw Mastery boosts your claw's physical damage by +111% and gives you +21% chance of critical strike. It also boosts your claw attack rating by +220%. Since Assassin weapon damage is boosted 75% by strength and 75% by dexterity, this level of CM is equivalent to adding 148 points to your strength stat when calculating your damage, and 220 points to your dexterity stat when calculating your to-hit ratio.
Act 2 Might Merc: A high-level Act 2 Offensive merc (from Nightmare) with level-20 Might will boost your physical damage by +230%.
Act 2 Blessed Aim Merc: A high-level Act 2 Offensive merc (from Normal or Hell) with level-17 Blessed Aim will boost your Attack Rating by +315%.
Amplify Damage & Decrepify: These Necro curses can reduce monster physical resistance into the negative zone. However, they will conflict with Cloak of Shadows. Aside from partying with a Necro, you can get 5% Chance to Cast Amp Dmg from Atma's Scarab Amulet [Gloves and 33% CtC Amp Dmg from The Lacerator winged axe. For a high-level mercenary, you can get 33% CtC Decrep from The Reaper's Toll thresher.
Fanaticism: Level-9 Fanaticism from a Beast rune word weapon will add +186% to your physical damage and +80% AR. Beast also adds +20% Crushing Blow and +25% Open Wounds.
Ignore Target Defense: ...
Enchant: At level-20, Enchant (plus max FM and Warmth) adds about 580 fire damage, reduced to 435 by Blade Fury. It also boosts your attack rating by +191%. Aside from partying with a Sorceress, you can use a Demon Limb club with level-23 Enchant charges on yourself, adding about 75 fire damage and +218% AR. Lava Gout Gloves have 2% Chance to Cast slvl-10 Enchant on Striking, which will add a small amount of fire damage and +101% AR.
Crushing Blow: ...
Deadly Strike: ...
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Open Wounds: ...
Prevent Monster Heal: ...
Perhaps the most frequently asked question about Blade Fury is this: which of the above types of damage and AR boosts works best with Blade Fury? While various players have different preferences, I think the key to success is to combine as many sources of damage and AR as you can. The truth about Blade Fury in Hell is that no single damage source will give you the power to kill as quickly as other characters' main attack skills. Unlike most other builds, there is no skill or weapon stat you can max that will do the job by itself.
Blade Fury has one additional drawback that can become a severe tactical disadvantage. When you spam Blade Fury, you're a sitting duck who can only rotate in place, much like a manually-controlled Strafezon. To do this safely, you need sturdy tanks and excellent crowd-control skills. Fortunately, 'Sins are well equipped to handle almost any situation in the game, whether alone or in parties.
Act 2 Merc — your main tank: Depending on your Blade Fury needs, choose either a Might merc from Act 2 NM, or a Blessed Aim merc from Act 2 Normal or Hell. In addition to his aura, the merc's main job is to stay alive and keep the hordes off your back. ...
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Shadow Warrior — your loyal subordinate: Unlike the headstrong Shadow Master, an SW will actually follow your orders and tank for you as well. This is particularly important when you're locked in place spamming blades at your targets. The SW herself will never use Blade Fury, but a normal melee attack instead, as well as any skill you select on your right mouse button. This allows you to effectively operate your SW by remote control at the same time as you attack with Blade Fury. This applies only to skills you have points in, but with a single point in Tiger Strike and Cobra Strike, you can instruct your SW to use charge-ups that you would never use yourself. She can cast traps and crowd control spells for you as well.
The Shadow Warrior's skill levels are calculated from your own: 1/3 of your Shadow Warrior slvl + 1/2 the slvl of each particular skill. Thus, every three points you invest in your SW skill will raise all of your Shadow Warrior's skills by one point. The Shadow Warrior's resists max out at 75% Resist-all at SW slvl-19. In NM and Hell, you can raise this by directing her to cast Fade on herself. Venom is another useful spell she can cast on her weapon.
Cloak of Shadows: ....Hell is now stocked with fleet-footed hordes that cannot always be neutralized by sheer firepower. In my experience, crowd control has become the most important factor to a character’s viability in Hell, with elemental resists a close second.
Cloak of Shadows vies with Dim Vision as one of the best wide-area crowd control skills in the game. It is arguably better than DV in that it affects champs as well as normal monsters, and lowers their Defense Rating as well. However, its drawbacks make it less flexible that Dim Vision, and I generally lay off Cloak when partying with Necros. Cloak is effectively a Necro Curse, and will override or be overridden by other Necro Curses, whichever is cast most recently.
The main problem with Cloak is that you cannot recast it until it completely wears off, several seconds after monsters start to recover from its blinding effects. For this reason, you want to keep Cloak’s skill level as low as possible to avoid having to wait for an excessively long-lasting Cloak to wear off. Fortunately, your Shadow has her own separate Cloak timer, and she can overlap her Cloak with yours. A tactic I often use is to select Cloak on my right mouse button, and allow my SW to take the initiative with it while I concentrate on Blade Fury.
Mind Blast: .... MB’s conversion side-effect is often annoying, forcing a party to wait until the last monster reverts before they can kill it and move on to the next pack.
Mind Blast’s stun effect, however, is always a useful backup to Cloak, particularly on monsters that cannot be converted. I pumped it up to slvl-11 for a 4-second stun duration.
Knockback: There's a rumor that knockback has been nerfed in 1.10 to no longer work effectively on ranged weapons. Maybe from a bowazon perspective, but certainly not as far as Blade Fury is concerned. I've spammed blades at countless thousands of monsters and not one of them has ever managed to struggle upstream far enough to land a blow on me. With Nef runes glutting the realms, there's little to stop you from adding Knockback to just about any weapon that doesn't already have it. In addition to weapons, Knockback is also available on Cleglaw's Gloves, Howtusk Helm, and Giant Skull Helm.
Slows Target by XX%: Many set and unique melee weapons have mods that slow monster movement after they've been hit. These seem to work like negative fast run/walk items, with multiple items stacking in an asymptotic manner. They're particularly effective for Blade FurySins who avoid cold damage in order to avoid depriving Death Sentry of corpses. In addition to weapons, Slows Target is also available on Cleglaw's Gloves, Blackhorn's Helm, Arachnid Mesh Belt, Noferatu's Belt, and Medusa's Shield.
Hit Blinds or Freezes Target: Many set and unique melee weapons have mods that give you a chance to blind or freeze your target. The odds are based on the ratio of your character level versus your targets'. Your chances are even better with Blade Fury repeatedly striking its targets at over 4 times per second. Note that Blinds Target will override Cloak of Shadows, but only on the targets you hit. In addition to weapons Hit Blinds Target is also available on Coif of Glory Helm, and Umbral Disk Shield. Hit Freezes Target is available on Iceblink Armor.
Death Sentry: Traps are generally useful to a Blade Fury ‘Sin, simply because they automatically target and fire on their own, giving you plenty of time to focus on Blade Fury. Death Sentry is arguably the best choice for a Blade Fury Sin, due to its huge area of effect at high slvls, and damage that scales up with increasing monster hit points. In addition, it does both physical and fire damage, making it effective against all but a very few bosses.
DS requires some restraint to make the most of its potential. If you toss them out prematurely, DS traps will fire off wimpy lightning bolts instead of corpse explosions, and you'll have to replace them after they wear out. Similarly, if you leave DS on your right mouse button, your Shadow Warrior will toss them around as soon as she sees a target, rather than waiting for the first corpse to drop. What’s worse is that you and your Shadow together can have at most five active traps at any point in time. To compensate, I started putting points in Fire Blast once I maxed my main skills. With every third point in FB, Death Sentry gains one more shot per trap, added to the five it starts out with.
Some players may be tempted by Lightning Sentry’s mutual synergies with Blade Fury, but to max LS, you'd probably have to pass on Venom. With LS, you need to put more effort into optimizing trap placement than with DS, distracting your attention from Blade Fury. In my view, a Blade Fury Sin is not really a Trapasin, she’s a ranged fighter who uses DS opportunistically.
Dragon Flight: With Burst of Speed available, a Blade Fury Sin is not going to feel a regular need for Dragon Flight. However, the ability to Teleport your merc, Shadow, and self right in a monster’s face is occasionally very useful when impeded by terrain barriers. It costs 4 skill points to claim Dragon Flight, maybe just a little more expensive than I would have liked.
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— RogueMage
(Edited by AK404 with permission, the original guide can be found here in its entirety.)