Necromancer's army build

Raise zombie: The zombies are your main protection, as they are extremely tanky, and take all the damage for you. They are linked to minion life-damage-speed and empower lvl 4 to always do some damage (the staff give them +2 gem level). As they have a lot of life, when they die (very rarely), they do some decent chaos damage over time (Beacon of corruption ascendancy node, about 3750 chaos damage per second per zombie). You have 9 zombies (+9% physical resistance for you and your minions thanks to the Flesh Binder ascendancy node, and +9% duration for minions from the staff).

Animate guardian: Your animate guardian MUSN'T die. It buffs your allies (minions + players) with its staff and helmet, and cast consecrated ground on block (4% life regeneration to allies in area of effect!). He is linked to the same support gems than the zombies to protect him, and get the +2 level from the staff too. The animated guardian has more than 30k life.

Summon skeletons: Your skeletons allows you to protect yourself from monsters. You have to summon them between yourself and the mobs attacking you. They aren't as much tanky as the zombies but they block enemies by their presence and do a lot of damage (quality on gem, high base damage, +2 level from the helm). They are linked to spell echo to summon them quickly. The spell echo gem doesn't lower their damage as they are summoned. Multistrike give them more attack speed. Thanks to the Femurs of the saint staff, they give a lot of attack and cast speed to your minions (that's part of the build synergy). You can get up to 12 skeletons.

Vaal summon skeletons: This gem is linked to minion speed to do more damage. It is useful with bosses (careful with the lags), and its only purpose is to do damage and buff your minions (more skeletons=more attack and cast speed thanks to the staff, sometimes you can get an anger aura from the gem with a mage general). You can feed the vaal gem souls in map before fighting bosses, and release it. After the skeletons disappeared (many seconds believe me!), you can use spell echo instead to boost the damage of your spectres.

Summon raging spirit: The gem is linked to spell echo to get more cast speed. The raging spirit do a lot of damage, take advantage from your auras, and above all can attack through locked doors and reach monsters at upper floors you can't access without any dash skill. For instance inside Beacon map, you can kill monsters with raging spirits from the beach without any risk! Multistrike improves their damage. The 20 raging spirits limit is easily reached. At the end of their duration, the spirits make the Beacon of corruption desecrate spawn, dealing chaos damage constantly.

Raise spectre: The spectres are the Frost sentinels which use ice spear (a different version than the player one, which gives additionnal projectiles and increased damage), pierce nearby ennemies with their projectiles, and reach a lot of them in the second form of ice spear (which chains and forks). They are linked to greater multiple projectile (switch to added cold damage support for bosses), empower lvl 4 (to give them more survivability) and minion damage support. Careful not to lose them.
You can eventually use with the feral chimerals instead, which deal as much damage but cast their projectiles less often (however they are more resistant to chaos and elemental damage, and they have suppressing fire which slows ranged attack and spell damage from mobs). If you do that, use slower projectile instead of added cold damage against bosses.
You have 4 spectres. If you find some at higher mob level in map, just refresh them (with desecrate) to get more damage (you can do that in the shaper realm for maximum efficiency). The flame sentinels are okay as spectres (I was using them before), but less powerful.

Summon chaos golem: The chaos golem ensure you some chaos damage (as well as the chest witch give your minions unholy might on kill), and some chaos resistances (the enchantment on the helm improve this effect). Thanks to the Brinerot mark unset ring, it does some good damage and is pretty tanky (+3 level).

Animate weapon: The animate weapons are linked to spell totem to be summoned quickly and easily (no need to modify your loot filter to show white weapons!). You can easily get 40 animate weapon in maps (50 max because of the gem number restriction), and it is a great source of damage. As they are many, they benefit a lot from auras (that's really strong with an auramancer in party). The increased duration gem + the duration nodes from the tree and the zombies related added duration from the staff allow them to last 100 seconds.

Convocation: The increased duration gem increases the duration on the life regeneration buff convocation gives to your minions. Convocation is useful to avoid your minions to die (traps, damage over time in an area of effect, minions in low life) or to protect yourself from direct damage.

Despair: the curse increase the chaos damage done by your golem and the raging spirits/skeletons when they disappear desecrating the floor. It adds some flat chaos damage which scale with the minion damage support gems, and improve all minion damage. +1 level from the boots.

Spirit Offering or Flesh Offering: The first one improve greatly the damage of your minions (except for the spectres, but elemental ones are better anyway), and provide you and them a lot of energy shield ( the Mistress of sacrifice ascendancy node makes the offering skills apply to you). The extra chaos damage is improved thanks to despair. If you're using flesh offering, all your minions will attack more often (really efficient with spectres), and you'll get more movement speed.
+1 level from the boots.

Discipline: Gives you and your minions more survivability. +1 level from the boots.

Vitality: Gives you and your minions more survivability. Useful with the labyrinth to regenerate life, as the witches don't have much life regeneration. Really useful to make your minions regen their life.

Spirits of the grave: They are summoned when your minions kills (3 at a time). You can get 6 of them. They are coming from the gloves enchantment.

Purity of elements: Give your minions some resistances they miss, and allows you to be overcapped with your elemental resistances without a lot of gear with resistances (the Commander of darkness ascendancy nodes allows you and your minions to get more resistances too). +1 level from the boots. It is an aura really useful with elemental weakness inflicted on you and your allies in party.

Flasks: the life flasks heal you and your minions (the first one slowly but efficiently, the second one instantly but a bit less). The Rumi's concoction flask (legacy! :D) allows you to block spells and damage (the staff has 12% block chance for attacks too). The quicksilver flask (I put a skin transfer on it, don't be surprised :p) gives you an anti-freeze and chill effect and some movement speed (not enough sadly). The basalt flask allows you to remove bleeding and get some physical damage reduction.

Other gear: The jewels give buffs to your minions (minion damage, elemental resistances, area of effect, soul eater to spectres, and chance to block), and to you (elemental resistances, silence curse immunity, energy shield, chaos resistance, and a bit of mana/mana regen). The chest gives you +1 spectre and minion damage, but you lose some minion life. The rare unset ring, the belt, the gloves and the helm give you elemental resistances. The amulet, the belt and the staff buff strongly your minions.

NB:

- The idea is to maximize the number of minions you summon, adding them enough life to be sure the one following you (except animated weapons, raging spirits, and skeletons) never die. The build is pretty focused on auras, because the more minions you have, the more useful auras are.
- The skill tree and the Beacon of corruption ascendancy node gives you some decent chaos resistance.
- I've tried to use conversion trap to get the buffs from the totems in map, and rallying cry to buff all the minions, but as there are not always totems in maps (and your friends will destroy them quickly) and the rallying cry taunts enemies, support gems are more useful than these 2 active gems.
- If you don't have any empower gem, use fortify instead, it gives strong damage mitigation and a bit of melee damage. However it is less effective.

Kill Kill Kill

Soul of Arakaali to reduce damage over time and shock effect on you (the lightning damage avoidance can be nice too but is a bit trivial)
Soul of Ralakesh to gain some immunities and reduce damage over time effect.

https://www.pathofexile.com/passive-skill-tree/AAAABAMDAAQHBLMGSQ18EJcRUBNsFScVUBZvFy8YVhpsHNwdqh_HIvQkqiSwJ6ko-iqYK3gsnDLRNuk5CzpYPC1Bh0QERUdFnUZxR4VJsUyzTblSKVNSVK5VxlXWVeBXyVhaWpFca2TnaHRo8mqsa9tsC20ZfRh90n5Zf8aApILHgwmDX4PMg9uESIVgiECMsY8aj0aQM5MnmuCbipuhna6hL6IApqynCKcrqH2qxLQMtz64k75Pvoq_l8BmwcXDbck9ytPMvNAf04_T-9fP2L3ZC9pi2t3fiuGI42rquuvu7IPsiu-I7-vwH_Ie99f5N_no-oD60v4K_kk=?accountName=Necronus2828&characterName=Soranssister

http://poe-profile.info/profile/Necronus2828

Amulet: Shade of Axiom and 2D skin transfer (blue pearl amulet)
Rings: 2D skin transfer (breach ring and Pyre)
Belt: 2D skin transfer (immortal flesh)
Helmet: Apprentice supporter pack set + doedre's scorn 2D skin (skin transfer) + ice crown effect
Body armour: apprentice supporter pack set + gloom wings
Boots: apprentice supporter pack set + 2D skin transfer (Sundance) + radiant footprints effect
Gloves: apprentice supporter pack set + 2D skin transfer (Wyrmsign)
Weapon: skin transfer (Taryn's shiver)
Portal skin and Social frame: any.
Skill effects: I am using the Carnage vitality, discipline forcefield and trinity purity of elements aura microtransactions, the ziggurat totem MTX, the ghostflame raging spirit effect, the summon statues skin MTX on Vaal summon skeletons, and the stygian effect on spectres. The tombstone desecrate effect is painful to see corpses, I don't use it
Pets: Nursery web spider pet, raven pet
Jewels: Just kidding, I did not put any skin transfer on them :D

- Go to the Lunaris temple in order to get some corpses to summon your zombies with desecrate. Summon your chaos golem, your animate guardian, and finally get the spectres. Activate your 3 auras.
- Then you can map. --> Summon quickly your skeletons, use spirit offering on corpses, curse enemies with vulnerability, put the animate weapon totem on the ground and finally summon your raging spirits. Use vaal summon skeletons when you find large packs of mobs or any difficulty.
- Convocation protects you if you need and prevent your minions to die (CAREFUL WITH YOUR ANIMATE GUARDIAN, it isn't cheap to equip him). Use your vaal gem when encountering some painful exiles/bosses.

Pros:
- You can clear all the red maps easily, and the build is Atziri viable (you can kill her without dying and quickly).
- The spectres can use ice spear from VERY far (Increased projectile speed support isn't even needed), killing mobs before they come.
- Really fun to play with all the minions around you :D
- You buff all your party members with your animate guardian, the Commander of darkness ascendancy node, and your auras.
- Your party members' auras buff you really hard.
- You can do maps with elemental and physical reflect, no mana regen,...
- Not even laggy since the patch note of the 22th of april 2017.
- Summoners are constantly buffed (just look at the patch notes), this build is stronger and stronger. Soon I'll update it with abyss jewels and stygian belts ^-^

Cons:
- Expensive build (many gems to level and to add quality to, you need resistances (including chaos resistance) and life on your gear, you need some enchantments you have to get through the lab, some stuff to equip your guardian, to vaal 6L items...)
- As you are playing life & ES, it can be a little risky when your minions aren't protecting you, you have to be careful and use convocation/summon skeleton just in case.
- You can't do the shaper, the minotaur, the phoenix, the hydra and uber Atziri. The Chimera can be killed though.
- You kill fast but your movement speed is bad.
- Not enough space to equip orb of storms in order to use elemental equilibrium (or else you must remove some minions)

With Frost sentinels: https://youtu.be/zJyHTlBGsto
With Feral plumerals: https://www.youtube.com/watch?v=LCAkZY06X5M

- Get a +3 level to socketed minion gems on the helmet now this affix exists.
- Get some minion speed on the rare unset ring with an essence of fear (That's gonna be really hard to find a ring with the resistances and that affix :p)
- Get a more interesting value on the corrupted implicit onto the amulet (RIP exalted)
- Finish to level the gems and to corrupt them to get lvl 21 or quality 23% depending on the gem.
- Get the updated version of kaom's root to equip the guardian (with dodge spell enchantment), corrupt the helmet and the gloves (as active enchantments don't work on animate guardians). The gloves would be cool with the curse with temporal chain on hit prefix (not even expensive!).
- Get a max rolled 6L Femurs of the saint.
- Instead of a +1 level of socketed gems corruption onto the boots, I should get a movement speed enchantment with a max rolled version of these boots.