So I tend to play arcanist quite a bit. I’ve played the CT builds some, and really enjoyed it, but always wished it had some more mobility. I don’t think there is anything much more mobile than a NightBlade, so I made a spell breaker. I originally wanted to dual wield, but did not like having little AoE. As I leveled, I got lazy, real lazy. Like so lazy I just wanted to run through as fast as possible, but still destroy everything in my wake. Also, I think this is also the most visually pleasing build I’ve made, but I like green colors so you may not agree 
Anyhow, this is what I have so far. 
Firstly, many thanks to Most for the CT build. This build was inspired by it, and copied much from it. Check out the thread here: http://grimdawn.com/forums/showthread.php?t=32768
Some game play: https://youtu.be/zNwQkYfK57E video keeps lagging. sorry about quality. new to this.
Here is a Cronley /Fabius run. https://youtu.be/iptYjm-RWR4
It was only my second time to fight Fabius, and he almost gets me twice, but i got him down in the end. Took about 50 seconds. I forgot to change gear and my bleed res was a bit low. eek You can see how you can literally run past most non-heroes and kill it through a chain of procs initiated by VoS. The damage is there, but my play style could use some help on Fabius.
Running Quest in Blood Grove and trying to use Arcane Will - https://youtu.be/BEgFFlCfA7U
Pics of gear: coming soon
The build: http://grimcalc.com/build/RumYyFp
Mechanics:
The basis of the build is using Veil of Shadow (VoS) to proc Agrivix’s Malice (AM), and gear with skills that have %chance to proc on attack. The goal was to turn on Veil of Shadows, and run. As you run it will continuously proc your gear skills, and AM. AM will also proc your gear skills. I use Shadow Strike (ST) for mobility, and the proc. The more “passive” attacks you can get in between AM procs, the higher its dmg. So I put my devotion points to Spear of the Heavens, Tree of Life, and Light of Empyrean as they don’t require an action turn. Spear of the Heavens seems to proc often, but it can be erratic. Light of Empyrion has been disappointing, but the points give good Res and fire dmg. It is also an easy gain since it has very similar point requirements as the Tree of Life. Tree of life is pretty great.
What I’ve found is that if you stay till the enemies are dead, except heroes, you’re wasting a lot of time/ damage. You really just need to build up the AM procs, and time it so that they will spawn where the enemies are, and keep moving. If you stay till every kill, you’ll see your AM procs doing their thing as you finally leave. So sad. They are just spinning around with all that damage and nothing to kill 
It’s important to remember that this build spools up dmg. Does not generate the big burst super well, but it seems to be able to kill quite nicely after a sec of two.
So take off and run. As you go you may need to attack with your CT depending on monster type/ your dmg/ monster density etc. As you go practice different techniques on mobility that generate the most “passive” attacks. Shadow strike into groups. Pop a Ct, and move on. Don’t recommend doing this in group play. It’s not so cool to be that guy who leaves the whole group behind stuck doing a jog behind you trying to catch up.
For heroes I ST in, pop nullification & Peerless Eye skill if needed, drop Devastation, blast CT. They melt. Fast. It’s also a nice debuff on the heroes for a party.
Skills: I like to max out both masteries. This gives you good base stats. In terms of a primary attack, you can pick either CT, AAR, PRM, or primary sword attack. Aether ray hits hard with aether, which will be your primary dmg dealer, but has limited AoE and tends not to jive well with a build based on mobility. CT has great AoE, and you can match the AoE up with VoS’s AoE. Gives you a nice visual for the size of VoS, and keeps you from slowing enemies before they are in range of CT. CT/Inferno also gives very nice monster debuffs for party. I don’t recommend PRM. I requires a lot of skill points, and is similar to AAR in mechanics. But any can work. You’ll have around 28-30 skill points to dedicate to your primary attack so take your pic. You could also go melee and use NB skills to deal the damage. Will really only need the primary damage dealer on heroes and up.
Arcanist
* Max These
- Inner Focus
- Devastation
- Reckless Power
- Your Primary Attack; I did CT/Inferno.
* Some Points in:
- Try to get 12 in Maivens Sphere of Protection
* at least 1 point in: (you have enough +1 to archaist that you get nice a nice bonus from just 1 skill point)
- Conversion
- Arcane will
- Nullification - great skill. I blast almost every hero with this.
- Mental Alacrity
- Fabric of Reality
- Iskandra's
- Overload
- Elemental Balance
NightBlade
* Max Phantasmal Armor - great passive
* Get up to 10 points in VoS
* at least 1 point in Nights Chill. More is not really needed.
* 7 or so in Pneumatic Burst (PB)
- 1 in Breath of Belgothian
- your discretion on other passives of PB
* 1 in Shadow Strike (ST)
- a few in NJE
* 1 point in Blade barrier
What you end up with is a fair amount of buffs for yourself and your party, and two invulnerability skills. I have found that I only need to use them against strong melee characters, or if reflect comes on when devastation is out.
Thoughts -
It’s not super tanky, unless you change the gear and go for more toughness. Iskandra’s could be an option here. I like being mobile, so the play style suits me.
You could go for a devotion setup that is more offensive. Would be nice to work in the widow. could give up LoE and maybe squeeze it in. Probably better in the end. A meteor devotion setup is also an option.
I’m not sure if there is a limit to how much you can stack up procs during the 1 second cooldown of AM, but if there isn’t this could really be a beast. I’m in the process of trying to get a bunch of gear with low cool down procs like “of the arcane blaze” gear. Seems possible to get VoS, SoH, LoE, 3CTs, 2 ring procs, gloves, etc… So like 9 or so? burn it up
Gear: You really only have to have AM. The rest should be built up around procs, and whatever you like. Here is what I have.
Head - Outcast’s Secret
https://gracefuldusk.appspot.com/items/8888-Outcast’s-Secret
Shoulders - Clairvoyant’s Mantle, some others ill try that have proc once they drop.
Chest - Clairvoyant’s Robe
https://gracefuldusk.appspot.com/items/7995-Clairvoyant’s-Robe
Gloves - Aethereach - good proc
https://gracefuldusk.appspot.com/items/7926-Aethereach
Gloves option - been thinking of trying Voidsteel since they have chaos res, good proc, OA and Cast speed.
https://gracefuldusk.appspot.com/items/7921-Voidsteel-Gauntlets
Belt - Phantom Thread Girdle
https://gracefuldusk.appspot.com/items/8212-Phantom-Thread-Girdle
Pants - Legwraps of the Tranquil Mind - is a good option.
https://gracefuldusk.appspot.com/items/8231-Legwraps-of-the-Tranquil-Mind
Boots - Wraithwalkers is what i use, but there are many options here. Pick one.
https://gracefuldusk.appspot.com/items/8016-Wraithwalkers
Relic - Agrivix’s Malice
https://gracefuldusk.appspot.com/items/2953-Agrivix’s-Malice
Weapon - WarpFire - reduce res all the way. Thought about switching up devotions to get the cold dmg from deviation due to conversion, but I don’t know how that would play out.
Off hand - Tome of the Arcane Wastes - many options here. this is a good one.
Amulet - Peerless Eye - cause its amazing
https://gracefuldusk.appspot.com/items/7776-The-Peerless-Eye-of-Beronath
Ring 1 - Incorruptible Cronley - suffix
Ring 2 - Incorruptible Cronley - suffix (of the Arcane Blaze is great suffix)
Ring Option - Band of the Eternal Haunt - proc of -%Res looks tasty.
https://gracefuldusk.appspot.com/items/7861-Band-of-the-Eternal-Haunt
Medal - Mark of Anathema - nice proc, comes often, large AoE. BoM is an obvious choice too.
https://gracefuldusk.appspot.com/items/8136-Mark-of-Anathema
Edit - 09-20-2016 added more gameplay. arcane will is pretty sweet
