I believe the videos will speak for themselves:

119% quant t16 conqueror map: https://www.youtube.com/watch?v=w5cxMr7sJjg

61% quant Shaper guardian invitation: https://www.youtube.com/watch?v=peq2K5xAqBU

PoB: https://pastebin.com/j2C2H2KU

This is an example of a mid investment build for the people who don't min max everything yet are past the usual league start issues. The total investment for this build is in the region of 10ex so far.

The idea is not original, but there's not many resources available for mid-investment builds. By mid-investment I mean that the build is happy to take on t16s, can do some end game bosses, but wont be jucing your invitations or doing 100% delirious. It's neither the 10c league starter nor the 100ex endgame build. It's for people like me, with limited budget or economical knowledge despite 1000s of hours in game.

The idea of this pathfinder is that it's a tanky mapper with the option of bossing. I am running Determination, Grace, Defiance Banner, Purity of Elements and using Iron Reflexes to convert all evasion to armour. The result is about 80k armour with flasks up. Because of pathfinder and the "gain charges on hit" flask mods, the flask uptime is pretty much 100%. This is crucial as I am using the Master Surgeon node, which means I recover 6% of life every time a flask is used. Most builds go for the Nature's Boon node which gives you a lot of flask charges but I don't believe this to be necessary at all, especially with the new eldritch modifiers on body armour.

Aura stacking is enabled by Devouring Diadem, which also solves all mana issues. The only requirement is that it needs to have the "increased duration of ailments when you focus" modifier on it, as it's a huge part of the damage output.

In maps, my 4 utility flasks trigger constantly. Coupled with high block chance (a blocked hit still counts as a hit, proccing my flasks), unless a single hit does more than 24% of my health, it will basically heal me. You don't really die in maps, but it's not an immortal build by any means. I have died numerous times, mainly to degen zones. There is basically no health regeneration in this build and you rely on the flask engine to survive. No hits = no flask charges. In that respect, a 4-way shaper guardians invite is in some ways easier than fighting the Shaper solo. You rely on the enemies hitting you frequently.

I have also opted to go the divine flesh route. Stacking max chaos res is not difficult this league. A +5% max res shield with +100 life only cost me 1ex. By comparison, a lot of top builds take the Brass Dome which gives you +5% max res in itself. The issue is that it's a strength base, and getting a 5G1B or 6W socket costs more than my entire build itself (11ex+ at the time of writing). Stacking chaos res also gives a massive dps boost from the chaos mastery "+1% to chaos damage over time multiplier per 4% chaos resistance". With 85% chaos resistance, this gives 21% chaos dot multi, as much as a malevolence aura.

A lot of PC league starters focus on just normal poison tree, but I believe that frenzy charges are key. This is in fact used by top a lot of builds on poe ninja - the difference is that at low-mid investment, the standard use of Snakebite unique doesn't outperform other options. In fact for most options, Snakebite performs worse than the modifer "increased attack and cast speed while focused" on gloves, which is an easily craftable mod. Coupled together with the helmet focus mod, damage is bumped up drastically when you focus.

Olesya's delight, a 1c unique, is a game changer. It got buffed this league and works wonders for poison builds, turning frenzy charge from 4% more damage to 8% more damage with ailments. On bosses, you generate the frenzy charges from a sword mastery - you path to Brutal Blade which gives you some % block chance, and pick the "8% chance to gain a frenzy charge when you hit a unique enemy". There is 100% frenzy charge uptime for bosses with this.

Withering step is another crucial part of the damage output. Leave withering step on left click, and it will just inflict 6 wither stacks on enemies every few seconds. Higher wither stacks options utilise spell totems, but I found that setup clunky and my totems did not survive very long. 6 stacks is realistic, if you see any PoB with 15 wither stacks you have to question how they get them consistently. It's too easy to inflate the damage like this.

I'd like to discuss the chest piece - currently I am running an uninspired rare. The main benefit are the eldritch modifers to block chance and flask charges. However Cherrubim's is great, Dendrobate is fantastic too; on a higher budget, a redeemer rare chest with chance to gain frenzy charges on hit would be fantastic.

This build is far from optimised. I would like to get a 21/20 divergent PC gem which will be a massive boost to damage, but that's too expensive. A 21/20 normal quality gem will be sufficient. The tree could probably take some tweaking. You could run Rumi's concoction to max out spell block.

High investment options would take brass dome, alternate quality gems to inflict more wither, forbidden flesh and flame to allocate way of the poacher for more frenzy charges. Alternate quality blood rage would save me going for the sword nodes and free up 6 points.

Happy to hear any feedback on the build, as I'm not finished with it yet.