Indigon Oracle Build + T16 Showcase

T16 (Pack Size, Magic+Rare monsters inc) + x3 - 3 to Clasped Hands Breach.

Uber Arbiter One shot: https://youtu.be/2KQcGkKOGd8
PoB: https://poe.ninja/poe2/pob/1a00f

What you need to do to make the build work:
The bread and butter of the build is the Indigon Magus Tiara helmet. Darkthrone Enthroned belt with Glove modifier (at least 100% effect) with the rune Quipolatl Thesis slotted inside one of its sockets.

The helmet will increase both the spell damage and mana cost of spells according to the amount of mana you have spent within the last 4 seconds.
The belt rune (Quipolatl's Thesis) will give you a % of mana back according to the cost of the curse *during* the time between when you cast the curse and it activates. So naturally Indigon and Thesis synergise EXTREMELY well together. The more expensive your spells and curse gets, the more spell damage you get and the more mana regen you recieve.

So how do you sustain the mana cost?
Well thats where the build gets a bit complicated, but don't worry, if you meet a wall theres plenty of ways you can tackle the problem. I'm now at a point where I can cast my Curse forever without ever needing to stop for the Indigon spell mana cost to wear off.
You need a combination of things, firstly you need a 5/4% to mana cost Indigon helmet, going above that will feel bad, you also need a Big mana pool, a lot of mana regen and a lot of cost efficiency on gear and passives. We even anoint cost efficiency on our amulet. You also need to balance your cast speed (not too high, but not too low either). Indigon only cares about cast speed to determine its cost of spells. So if you notice you stop casting, you need to either increase your mana pool, cost efficiency and mana regen, or you need to reduce your cast speed slightly. This can get tricky because it depends on your gear, so its highly individual how you go about fixing this. But if you use my PoB and tree as a guideline you should get to a balanced build quite comfortably, even though you have slightly worse gear than me.

To get a big mana pool we want a Max mana and mana regen everywhere we can get. You need at least 7k mana pool for the build to feel good. Rings, amulet, chest and a good pair of corrupted Idle Sanctioned Bracer gloves are the main contributers to this. Since we have Eldritch Battery, ALL of our Energy shield gets converted to mana. So high energy shield on chest and boots are important (especially chest). You also want all the cost efficiency and mana cost efficiency you can get (Cost efficiency corruption on gloves), and passives + runes/anoint.
Around 2.4 casts per second is usually a good middle ground for your curse spam to feel good and to help boost your mana regen and indigon damage quickly enough. I'm at 3.49 CPS and can still sustain it, but my gear is ludicrously minmaxed, this just goes to show you how far you can push the build if you invest into it.

The build can reach upwards of 5000% spell damage and 100k mana regen with enough ramp. I'm basically oneshotting Uber Arbiter and ignoring all his mechanics. I've seen Arc hit for 20mill+ with some nice ramping.

After you are at a good spot where you can sustain your spell costs, you invest into crit damage and some crit chance. We are using a Malice sceptre to boost our crit chance on tough mobs and bosses who don't die instantly. And we also heavily abuse Entwined Realities ascendency node on Oracle to take advantage of stupidly strong Time-Lost Sapphires. You want two Large Time-Lost sapphires with Mana cost efficiency, (one of them need Curse area). Luxury is crit damage on them as well. And you want one Crit + Max mana Time-Lost for the third one.

We also use Kurgals Undying Hate to transform a keystone to "Sacrifice of Mind" to let our mana overflow 1.5x.

We use Mind over Matter so that our mana is our life, with the amount of regen and high mana pool we get we are incredibly tanky unless we get oneshot or stunlocked.

The reason we also need so much mana regen on passives and gear is because MoM and Kurgal will reduce our regen quite a bit. While Quipolatl will give use tons of mana regen we also need some extra to make it feel good.

Bossing/Mapping and Curse AoE:
For general mapping we cast 3-4 curses between packs to get a nice regen going and then cast Spark to trigger Arc. The Curses also deal great damage but they activate slowly due to Whispers of Doom Keystone and Ritualistic Curse support.
You need to have Deordre's Undoing and Spell Cascade supports as well. Spell cascade will triple your curse giving you 3x mana Quipolatl's thesis regen back and Undoing will let your curses deal damage. On Bosses we only cast curses since you always get time to have TONS of them ready for when the boss stops it's intermissions / intros. Curse spam is also the best and safest way to scale Indigon damage. For bosses it will feel extremely good having 4.7M Curse Area, since it will make all the curses overlap eachother and will proc 3x Deordre ticks each cast on boss. However, its not needed for the mana regen and general mapping. But I highly recommend reaching it eventually so the build becomes great at tackling everything the game throws at you.

The build feels extremely fun to play and I hope someone will try it out. If you have questions I will gladly answer them.