Theory/Background - (The Why)
This build is made possible by the newly revised Holy Point Shot quiver. With the new quiver, impale will throw 3 knives instead of one. Each knife gains the 6p bonus damage from the Shadow Mantle Set. Currently its also possible, if positioned very close to a mob, to land all 3 buffed impales on a single target. So for instance the RG will take 3x the damage from impale than it does w/o the Holy Point Shot if standing very close while attacking it. This is an awesome change. This will greatly increase the effective damage output for impale. Not only that, all 3 knives will return the amount of hatred that is listed on your Karlei's Point dagger. Now with up to 3x the refunded hatred, it is no longer necessary to have a generator, while staying at near full hatred most of the time. This allows using and taking advantage of the Aquila Cuirass chest in the cube for 2x toughness.
Gearing/Game Play - (The How)
Make sure to have at least 36.7% cdr for permanent Vengeance. The required cdr can be accomplished with cdr rolled on one piece of gear, 15% cdr from the Gogok of Swiftness, a diamond in helm and 10% cdr in paragon. Tactical Advantage passive is desirable to use for speed runs. Use Leech for soloing higher GR's. Numbing Traps can be used to buff group toughness if needed. Single out should be used when pushing high GR's in 4man groups. Nemesis bracers are an excellent alternative to Strong Arms and are recommended for speed rifting. For pushing GR's in 4 man's, Lacuni Prowlers can be used for increased attack speed to better stack Stricken. For bounties there is no better choice than the Warzechian Armguards. For pushing high GR's with supports, wear an SOJ and cube the Convention of Elements for more damage, since the with supports the Elusive Ring may not be needed.
Try to stack life after kill on chest, belt, pants, jewelry and weapon if possible. Life after kill works beautifully with this build. Shadow Power will add 50% of your life after kill to life on hit, the leech passive adds another 75%. Together you will have 125% of LoK as LoH. This is a huge gain in health recovery, allowing for safe passage while playing very aggressively.
Note that if you play at a game difficulty where you are one shotting mobs, it will result in running out of hatred because there will be no opportunities for hatred refunds from Karlei's Point. Some examples of where you might run into this would be power leveling friends or running fast low level GR's to level gems. In order to mitigate this problem so you don't run out hatred, run Seethe instead of Dark Heard, replace Cull the Weak with Blood Vengeance and replace Aquila Cuirass with Visage of Gunes in the Cube.
Make sure to spam Vengeance, bladed armor and wolf when off cooldown. The constant activation of these skills can be achieved by num locking them. Beyond that, all that is required is to cast impale to attack and vault for mobility. Its really that simple. You do need to make sure to impale every 2 sec in order to have free vaults. I personally use vault actively to stun elites and RG's to interrupt their special attacks. This can be be extremely helpful in surviving nasty fights. Note that while vaulting you enter into a smoke screen like state that renders you invulnerable to incoming damage for the brief time you're traveling from point to point. Make sure to keep the elusive ring buff up at all times. This can be done by vaulting or casting shadow power. If you find yourself placed particularly well, as in next to an elite that you are impaling, casting shadow power to proc the elusive buff is preferable to vaulting if you can face tank well enough to stay in place. Note that this build requires hunting and killing mainly elites, especially for speed runs, but higher GR's will require gathering up and killing large packs of trash also. Just make sure to take advantage of the oculus circles when doing so.
Summary/Wrap Up - (The Results)
The build is very simple to play and a hell of a lot of fun. It gives insane mobility, good damage and high survivability. In fact fully self buffed with all dps gems and nems, its not uncommon to exceed a toughness of 600 mil at low paragon. That's awesome toughness for a dps class with no support. I have tested this build on the PTR for patch 2.5.0 in HC. In Season 10 with 1.07 mil sheet dps I cleared a GR 82 in 9:43 on the first attempt. This build can be used to compete for pushing the highest GR's for both solo and group play. For speed farming it is superb. GR 75's are taking under 4 min to clear (with 2 mil+ dps). Normal rifts are fast and fun. Split farming 4man T13 bounties is very doable once geared well. In short the build will do everything you need and want within Diablo 3.
I have thoroughly enjoyed playing and testing out this build and I hope you will find as much enjoyment with it as I have. Please leave a comment below if you have any questions. Please Upvote if you find this guide useful. Thanks.