The Agnostic Hierophant + Ice Nova + Frostbolt + Righteous Fire

Use new Militant Faith Jewel for the Agnostic Keystone, to get this the jewel needs to have Venarius in the jewel description and it will transform keystones near jewel nodes to the needed keystone.
Defensive - Gets 50% MoM with huge mana regen along with some small life regen. This huge mana regen combined with The agnostic keystone allows for Sustain that feels like permanent vaal pact slayer overleech.
Offensive - The new pledge of hands greater spell echo is busted when using with the ice nova frostbolt combination because it gives 4 repetitions when using spell echo on 3 frostbolts per 1 cast which is like a 12 times multiplier not accounting for additional more damage for each repeat. Broken and probably will be nerfed, but one can also tack on even more damage with righteous fire and vaal righteous fire to delete opponents.
Auras:
Clarity - for watchers eye mods
Precision - for critical strike chance(hardly reserves any of mana pool
Zealotry or/and Hatred with an essence worm can be used if you have a good watchers eye but completely unnecessary. Youll see im using 2 essences worms because I was min maxing some damage output, but in all honestly if you were rocking 2 good mana/life/ele resists rings with damage gained as mana mod you would be extremely tanky

Pros
+Budget *MID league to get started
+High EHP
+Massive Life/Mana Regen
+Mobs and map bosses can't one hit(except things like atziri flame blasts, but you will instant phase her)
+DPS viable for endgame content
+Hardcore Viable
+Can run all map mods except no regen/ele reflect
Cons
-Not clear speed meta

Weapon - Use dual axioms until you can get pledge of hands at lvl 65/68(i forget)
The reason for using pledge of hands as BiS is this: increased mana is pretty good but the damage is broken and basically comes down to the way spell echo interacts with ice nova being cast on frost-bolt. The mechanic is BROKEN. The new pledge of hands has greater spell echo, which makes spells repeat an additional 2 times with 35% more damage per repeat. So if I cast ice nova with spell echo as well, it repeats 3 times. If I cast it on a frostbolt, The repeats will occur on the frostbolt with out me having to be locked down casting 4 times. Effectively, I get 4 ice nova casts per 1 cast, with 70% more cast speed of spell echo. On top of that, Ice nova occurs on 2 additional near by frost bolts, so for every 1 cast I get 12 ice novas occurring. Basically, with no investment this mechanic feels like a 1200 crit multi build with 100% chance to crit and I can invest in a separate crit multi scaler

Gloves - New maligaro's virtuosity is worth 150 crit multi and 50 crit chance if with no investment into crit multi, with investment in, one would only barely hit above 300 crit multi total so these gloves save a ton of passives for huge damage(super underrated)

Belt - just use a belt of deceiver or any rare belt with resistances until you can get a shaper belt with mana recovery rate mod

Boots - Dance of the offered, gives mana and perma onslaught - can wear till endgame, i wore up until i did shaper and only had to switch when i needed res because i picked up a second essence worm for hatred. Sidenote, a 2% mana and HP regen enchant would be GG for this build on boots so just buying a pair with that mod would almost double your sustain.

For helmet - I would recommend Indigon for maximum DPS, but the helmet I used maw of conquest was cheap and effective

Rings - I used two essence worms, but I would recommend mana/life/ele resists rare rings for a more well rounded character, the character doesn't really need the extra damage

Body Armour - Cloak of defiance, gives a ton of mana, %1 Mana regen which is extremely important and mana taken from mana before life

Amulet is atziri's foible all day everyday, hard to compete with 130 mana regen rate +20% mana and 100 mana, plus the reduced attributes stat is very useful

In your pledge of hands you want -> Ice Nova -> Spell Echo -> Cold Penetration -> Increased Crit Strikes -> Ele Focus -> Controlled Destruction (didn't PoB these for best links, but tried to put them in relative order of what I prefer for damage and mapping)
Then only other links id setup are frostbolt -> GMP -> Onslaught/Slower Proj(for bosses)
and A orb of storms with curse on hit frostbite and power charge on crit
finally I recommend using flame dash for mobility and frost bomb for cold exposure(-25 cold res) on bosses
Vaal Righteous fire -> duration -> you can constantly have righteous fire on and use vaal when you need to dps stuff.

Soundless Shaper Kill
Uber Elder Kill

Pastebin: https://pastebin.com/JMhFJLEC