The build of this T13 speed run and future GR85 speed run is to focus on maxing your damage. To do this, you use Impale to provide up to 3 free vaults. This allows you to run and travel faster. The Bracers let you pop shrines as you will be ahead of the group most of the time, unless there is a charge barbarian in the group, which then switch to Strongarm bracers so you can have the increase damage on stun enemies.
Since this build uses no other CD's in theory, your Obsidian Ring of the Zodiac will only lower the CD of your Vengeance ability, unless you use your Preparation or Companion for some reason. (Please never use Companion as you gain nothing from it, the passive is there for 10% MS)
Preparation provides 20 additional discipline. This equals to 33% more damage or 2000% damage from the 6 pc.
Overall, this build will have over 100 discipline. Which means your Multishot will be doing at least 10,000% Weapon Damage. While this is nothing in comparison to say Impales single shot 50,000% weapon damage for single target, the goal of Multishot is to spray kill vs single kill. This is why Multishot is the best speed build in the game. You can use this same build for Bounties if you want to collect those items for the reforge legendary which has a higher chance of ancient/primal rolls than if you just use Death Breaths to upgrade yellow (rares) to Legendary/Set gear.