[2.1] Acrobatic Arc - Crit Arc/Phase Acro/VP, Talisman skill tree updated.

Pros:
-Good survivability. Great chance to dodge/evade attacks(for a spell caster :P) and 46% chance to dodge spell.
With Vaal grace, 10sec 70+ dual dodge!!
about dodge see here http://pathofexile.gamepedia.com/Dodge

-Nothing else especial. xD

Cons:
-dps around 25k with penetration. Yes, it's a bit low compare with powerful crit spell builds...

about Penetration, see here http://pathofexile.gamepedia.com/Penetration
-Some gear may get in late game
-It's not easy to get enough mana regeneration to cover the 6L mana cost.
-Damage Over Time is deadly. Bleeding kills you in seconds if you run without notice. (especially bleeding + cursed with vulnerability, poison cloud, desecrated ground, and bleeding stack by monsters have 'Corrupting Blood' Nemesis Affixes)

Jewel option:

lv90
.
lv70
.
lv50
.
Bandits:
Normal help Oak/ Cruel kill all/ Merciless kill all

You can start with shadow/witch/scion.
take life, mana, crit, level up as crit Arc.
You may transform to acrobatics around lv80.
Need around 210 mana regeneration per second to cover the mana cost of 6L arc. 'increased maximum mana' from tree and '+xx to maximum mana' from gear are very valuable.
This build has around 120% increased mana regeneration rate from tree and another 120% from gear.

There is a half/full cold damage version of ARC.

I prefer full cold version. Safer by freezing packs, no shock, no HoT though.

Atziri's Step is core item for this build.
For the rest of them just grab resist/life/mana/mana regen as much as you can.
And eva/es type armours suit this build well.
I prefer stacking resist over 142%, so I still have my resist cap with lv19 purity of elements while doing 'cursed with elemental weakness' maps.
If you have difficulty in reaching 135% resist, there are a few options from skill tree that could help before you get enough from gear.

and

5L/6L Arc

Remove 'Increased Critical Damage' if 5L.
DO NOT replace 'life leech' with emp/chaos dmg... for higher dps,
It's like eva/dodge + practical application give you 0.5 second above water, life leech is the one breath you need to take.

Replace Lightning Penetration with Cold Penetration if you play full cold version with 'Call of the Brotherhood'.

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4L #1 CWDT set.
or
Or Warlord's Mark for extra leech.

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4L #2 Buff/Aura


On-demand option

Try get a BBGW 4L for this set, easy swap purity of elements(fire/ice/lightning) means better adaptability.
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4L #3 Vaal Grace / Vaal haste / Golem


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3L #1 Curse on hit


Normally HoT works great, if you play Full cold version ARC, take HoI.
Once you shatter an enemy, HoI triggers Assassin's Mark curse nearby enemy.
It's very helpful to curse pack of monsters that out of HoT range.
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3L #2 Movement

Since you have eva/dodge and practical application (40% chance to avoid interruption from stuns while casting), 2.2% instant leech. You don't have to keep distance from pack of mobs all the time.
Most of the time, even surrounding by magic monsters, just hold the arc button, use diamond flask/Atziri's Promise.

One gear change
You don't really have to use Rise of the Phoenix if you are familiar with Atziri's fight pattern. I defeated her with Voltaxic Rift once for fun.
Skill change:
Because of damage reflection by Atziri's copy(the one with a mirror), obviously arc is not a wise choice. We need a lighting spell that focuses on single target.
6L: Switch 'Arc' and 'increased critical damage' to



4L #1 switch 'cwdt set' to 'Arc + spell echo + faster casting + empower' to clear Atziri's flask xD.
You don't need physical dmg immunity when fight Atziri, most of her moves are elemental spell.

4L #3 switch HoI to Purity of Fire. 87% Fire resis you should have with Rise of the Phoenix.

info about Atziri http://pathofexile.gamepedia.com/Atziri