A pretty straightforward build revolving around the reworked Ralakesh's Impatience and stacking all kinds of charges for a ton of generic spell damage.

Mid-budget PoB: https://pastebin.com/yZu8bnEW

####Core Mechanics:

• Use the boots for an easy way to generate all types of charges, without having to kill - Requires usage of a spell that hits instantly or snapshots damage on cast (I'm using Arc and Crackling Lance but other spells work)
• Badge of the Brotherhood and Slayer's Masterful Form to stack Power Charges and get 3 for the price of 1
• Malachai's Loop for +2 power charges and a bunch of spell damage, using Tempest Shield to become immune to its shock. You don't lose the charges since your minimum power charges = maximum
• Arn's Anguish for 30%+ chance to deal triple damage with Brutal Charges, also grants pseudo stun immunity all the time since moving doesn't get rid of Brutal Charges
• Inner Conviction (from Dominus's Militant Faith) to get 3% more per Power Charge, ignoring the downside since we get minimum Frenzies

Bonus Mechanics:

• Some ailment effect with Arn's Anguish triple damage bursts to max shock/freeze most bosses
• 30s Onslaughts from Rotgut with a bunch of minimum frenzies
• Eldritch Battery to run Blessing Zealotry + Frost Shield since our spell usually requires us to stand still, Frost Shield is a nice boost to survivability and damage, effectively turning 730 of our ES into 60% less hit damage
• Situational 100% Cooldown Recovery Rate from Badge of the Brotherhood lets us Dash around a lot, Phase Run on left click makes us go faster
• Slayer overleech to run RF for general mapping
• Forbidden Flame/Flesh for the (relatively) cheap Champion Conqueror gets us another -10% reduced damage stacking additively with Brutal Fervour and Soul of Arakaali for 30% total reduced damage from RF
• Basically no 'on-kill' buffs so you can loot leisurely

####Budget:
Minimum Requirements:

• Ralakesh's Impatience, Badge of the Brotherhood, Arn's Anguish, Malachai's Loop = 80c~
• Bitterdream = 1c
• Rotgut = 1c

This gets you around 1.2m with Crackling Lance, 800k with Arc

Milestone Upgrades:

• Dominus's Militant Faith - 30% more = 40c
• +1 Power Charge Corrupted Helmet - 30% more = 20c
• Bitterdream -> Void Battery + 5L - 50% more = 2div~

Potential Upgrades?:
Cast speed on rings, especially with Kalandra rings (Good for stacking Crackling Lance Intensity)
Warlord + Corrupt Double Power Charge Helmet
Enlighten 4 to squeeze in Herald of Ice
Juicy Precursors for +Power Charges

Closing thoughts:
I wanted a cheap league starter that would work well out of the box, and this has been running pretty smoothly, getting up to yellows with a Bitterdream (though I was hoping Ralakesh's Impatience would be a 1c unique). Slayer culling has made most AN rares unnoticeable until T16s but the build might be better off as another Ascendancy and dropping Arn's Anguish. Defences don't scale terribly well into the late end-game even with Grace instead of Heralds but the damage has been one of the highest I've played with this level of investment (My current PoB: https://pastebin.com/SAzaeZ6u), if anyone has any ideas to make it way tankier I'm all ears!