This build plays upon the strengths of Trag'Oul's 6-Piece set while also granting huge mobility.  Every part of this class plays well with each other.  Your Bane of the Trapped along with Krysbin's are going to be proc'd heavily due to your constant stuns.  Your Lornelle's is going to benefit from the health drain of the Skeleton Mages, who in turn benefit from Trag'Oul's 6-piece set bonus.  This is a generator-less class.  Your essence will instead come from Devour and picking up health globes.  Because of this, it might be suggested to re-roll some of your pieces to increase the range at which you can pick up health globes.  All in all, this is a fast trash and elite clearing build that will allow you to speedfarm/speedbounty/speedrift without much trouble.  There are lots of trade-offs in damage for increased survivability, speed and mobility.  As such, this build is not suitable for GR progression. 
Gear And Cube
Weapon: Jesseth Skullscythe
Off Hand: Jesseth Skullshield - We want the set bonus from having both of the Jesseth items equipped.  Command Skeletons is going to be your main "attack", as it allows you to focus your pets on a target.  Having this set bonus keeps your skeletons commanded as long as there are enemies on the screen, and it powers up your Skeleton Mages.
Belt: Krelm's Buff Belt - For the speed buff.  If movement speed is less important to you than damage (for example, if not playing on Season 16), then you can replace this with The Witching Hour.
Wrists: Reaper's Wraps or Nemesis Bracers - The Reaper's Wraps are are craftable.  I'd recommend these for running bounties/goblins.  For speedrifting, go with the Nemesis Bracers.
Head: Trag'Oul's Guise
Chest: Trag'Oul's Scales
Shoulders: Trag'Oul's Heart
Hands: Tasker and Theo or Trag'Oul's Claws - Use T&T if playing on Season 16, otherwise take the Trag'Oul's.
Legs: Trag'Oul's Hide
Feet: Trag'Oul's Stalwart Greaves
Ring One: Krysbin's Sentence - This will proc nearly all the time with this build.  Super powerful ring.
Ring Two: Lornelle's Sunstone - This is an odd take for most builds, but with a good roll, you can get +Int, +CHD, and +CHC as well as pretty great damage reduction on this ring.  For that purpose, this ring is mandatory.
Neck: Wisdom of Kalan - This could be substituted for a more damage-focused neck, like The Johnstone or a Hellfire Amulet with good stats and a good passive.  The extra 5 stacks of Bone Armor will help our movement speed, however.
Cube Weapon: Scythe of the Cycle - Straight up Skeleton Mage buff.
Cube Armor: Steuart's Greaves - If not playing Season 16, you could put Tasker and Theo here.  However, the movement speed buff is incredible.
Cube Jewelery: Circle of Nailuj's Evol - Another big Skeleton Mage buff.
Skills and Runes
Left Click:  Bone Armor, with the Dislocation rune.
Right Click: Blood Rush.  Rune doesn't matter, since Trag'Oul's will give you all of them.
1: Skeleton Mage, with the Life Support rune.
2: Command Skeletons, with the Frozen Grasp rune.
3: Land of the Dead, with the Frozen Lands rune.  I hardly use this in my runs, as it's not really necessary.  It's more of an "oh *filtered*!" skill I use in emergencies.  That said, this is great against bosses.
4: Devour, with the Devouring Aura rune.  Your biggest essence generator.  The rune just makes it easy to manage, but if you like pressing buttons constantly, take the Cannibalize rune.
Passives: 
1: Dark Reaping
2: Grisly Tribute
3: Overwhelming Essence
4: Final Service
5: Extended Servitude - Only take this if you've got a Hellfire equipped that gives you one of the above passives.
Stats:
Int should be your main stat.  The following three stats are my recommended priorities in order after Int: +%CHC, +Armor, Gold/Health Pickup range increase
Paragon:
Paragon Priority should be :
Core: Movement Speed > Intelligence > Maximum Essence > Vitality
Offensive: Crit Chance > Crit Damage > Cooldown Reduction > Attack Speed
Defensive: Armor > Resist All > Life Regen > Life
Utility: Life Per Hit > Resource Cost Reduction > Area Damage > Gold Find
Gems:
Helm - Diamond
Chest - Two Topaz, one Amathyst
Legs - Two Topaz
Weapon - Emerald
Anything not jewelry - Topaz
Jewelry - Bane of the Trapped, Enforcer, Bane of the Powerful
Playstyle:
This build has an odd playstyle.  Aside from the small output of Bone Armor, you are not going to do any damage directly.  You're going to pop Blood Rush as much as you want to zoom around the map.  When you encounter enemies, you want to get near them and pop Bone Armor.  After that, Command Skeletons to one of the enemies (you can pop this multiple times per encounter.  Whoever you target with this will become your damage priority.  Then pop exactly 5 Skeleton Mages.  While your pets do the work, Blood Rush around the pack of enemies in order to Devour corpses to restore your essence.  Pop Bone Armor as it becomes available. 
Just do this from pack to pack and you'll be fine.  I've been able to clear Act II bounties in less than 7 minutes, a Golbin Farm run in less than 4, and a regular rift in under 2.  This is all on T13, by the way.  I am Paragon 590 as of the writing of this post.
If you find that you aren't doing enough damage, remember to make sure that your Skeletons are always Commanded.  If you don't command them, you're losing out on the damage bonus granted by the Jesseth set.  Also, make sure you keep 10 Skeleton Mages up at all times.  This equates to casting it 5 times, if you have Nailuj's Evol cubed.

Where do I find the best set ups for characters on Diablo 3?
 

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