I think I'd share my most successful build this league, which I actually started with. I had an absolute blast playing this build, so if some of you guys looking for inspiration maybe it's the one you need.

I've done all content in the game including Awakener 8 The Feared and 100% Delirious maps (this one is not so comfortable, but doable). Simulacrums are cakewalks. Everything in maps dies like it's nothing. Sometimes she kills map bosses without me noticing it. In her current state she is worth around 100-120 exalts, but she can work with much much less (it's my league starter after all). She is still not maxed but I don't think I'll go any further.

Pastebin: https://pastebin.com/M69Tzi1Q

Main points: this is non-crit (we use elemental overload) Golementalist who uses Ball Ligthning with Archmage support as main skill. She uses 4 golems: chaos, flame, lightning and stone. Arcane cloak is our guard skill. Amount of unreserved mana 9k+. DPS calculations for Ball Lightning in PoB are way off, but she kills bosses VERY fast, especially when you switch to Slower Projectiles instead of Greater Multiple Projectiles (not always the way to go. For expample, I fight all boss arenas only with GMP which allows me to hit stuff offscreen without aiming).

This build has very simple almost braindead gameplay: you don't need to spam a lot of skills, re-summon stuff, press flasks all the time, etc.

Mandatory items are The Holy Trinity of archmages: Pledge of Hands, Cloak of Defiance, Atziri's Foible + Crown of the Inward Eye, and Nexus Gloves or other ritual base with the same implicit. It allows us to make every 3rd cast free while preserving the damage.

So what is up with all these spheres?

Hydrosphere is a perfect source of lightning exposure: huge aoe, easy to move around, great for procing Elemental Overload. It is also a great vehicle for our curses (Elemental weakness, Conductivity) when paired with Awakened Hextouch support. I also support it with Elemental Proliferation. Paired with nodes Ash, Frost and Storm, and Holy Dominion it gives our Hydrosphere and Void Sphere 40% chance to shock, freeze and ignite.

In practice, it means that when you map and move Hydrosphere in front of you, packs of monsters get frozen most of the time and then shatter from Ball Lightning, unable to do any harm to you. This setup also allows us to utilize Sadist and Snowstorm nodes on cluster jewels.

Void Sphere is very underrated but very powerful utility spell which is often overlooked. In my build it is in the same setup as Hydro (so it also curses mobs) but you can use it even with no supports at all. With content like ritual or harbingers introduced in this league, it makes huge difference. I could use something like Vaal Rightheous Fire to boost my damage instead, but honestly, this build deals enough already. And btw Void Sphere is SICK when clearing Harvest crops.

Both Hydrosphere and Void Sphere greatly benefit from Heart of Destruction ascendancy node, gaining huge AOE when mapping.

Auras I use are Clarity. Vitality, Wrath (in Essecne Worm Ring)

Mana is restored via mana regen on nodes and items, clarity aura and Mind Drinker node I got via annointing the amulet. No need for mana flask - it doesn't do anything, the amount of mana even the strongest flask restores is too low.

Worth noting that this build has very good defences: 39% physical reduction without Rumi flask and endurance charges, and 68 when we apply those. I also use Glancing Blows and have 40% attack block and 75% spell block. Attack block reaches 75% with Rumi flask on.

Main defensive mechanics I use: Arcane Cloak (no comments needed), Glancing Blows, some block nodes on the tree, mod on Watcher's Eye giving us 10% of max mana as Energy Shield, Stubborn Student cluster node which gives us 1 armor for every 10 of maximum mana which results in 8% additional damage reduction, Endurance Charges on boots (Elder influence, this one is kinda luxury mod, you can be fine without it), Vaal Grace at lvl 11 for harder situations.

So, I'd be happy if it helps anyone and will gladly answer any questions