Hi all, Surgeon General here.

Discharge scales it's base damage with the number of charges expended on use. The Discharge Slayer build stacks maximum power charges and then uses Masterful Form and Badge of the Brotherhood to raise the maximum of the other charge types as well. With 10-11 of each charge, you get 40-50k base damage; quite strong. However, it's hard to scale that damage against enemy resistances because its spread out among the three elements.

In Mercenaries league, you could get around this problem with The Admiral and a Doryani's Prototype merc, multiplying the damage of the build by like a factor of 4. However, the typical slayer build setup uses Farrul's Fur or its Replica (with some reduced duration on Aspect of the Cat) to generate the charges needed to use Discharge on cooldown.

If you could find a new way to generate charges with reasonable reliability, you could free up the body armour slot for the busted Admiral/Doryani's combo.

The Tech

Some of you may have seen my previous post about generating endurance charges by proccing when-hit effects with self damage from Scold's Bridle and Bladefall of Trarthus.

You can generate all three types of charges by using the same combination along with Supreme Grandstanding.

Supreme Grandstanding grants "Enemies Hitting you have 10% chance to gain an Endurance, Frenzy or Power Charge." However, it seems that the way this is programmed in-game is that when your character is hit, it gives the source of that hit a charge 10% of the time. With self-damage, since your own character is the source of the hit, that charge goes to you.

This "bug" has been in the game in past leagues but it hasn't been very reliable. With self-cast abilities, the 10% chance wasn't high enough to generate charges at a meaningful rate for Discharge. But with the introduction of BFoT, you can automate the Scold's Bridle self-hit process to occur on every server frame. With 30fps and a 10% chance to gain a charge, you get on average one of each charges per second. That's not quite enough by itself, but you can amp this rate up with two effects:

First, you can just take Inexorable as discussed in my previous post, completely solving endurance charges. You can then use Inya's Epiphany and a frenzy Precursor's Emblem to get sources of "when you gain a charge, instead gain up to maximum charges" for both power and frenzy charges. This effect can proc whenever Supreme Grandstanding procs, instantly filling that charge. You then supplement your frenzy and power charge generation rate by spamming Frenzy linked to Power Charge on Crit Support while Discharge is on cooldown.

Combined, this is enough charge generation to have better than ~80% uptime (rough estimate) on max charges when Discharge is off cooldown. While the uptime is less reliable than with Farrul's Fur, 80% uptime on 400% damage is better than 100% uptime on 100% damage.

The Build

Here's a PoB for my current setup; merc and AG gear in the alternate equipment sets. Average hit is something like 170M. Some people will definitely find the playstyle clunky, but it's quite reliable to one-shot anything below an Uber and charges are always pre-loaded for bosses with the Grandstanding tech. It's a better bosser/invitation farmer but mapping is possible too. Mobs with spell block, proximity shields, and maps with tight corridors are annoying though.

The passive tree is pretty straightforward. You're just getting max power charges by pathing all the way west then north, getting life, block, and spell crit/multi on the way. Mandatory nodes are the +1 max power charge nodes, Inexorable, and Supreme Grandstanding. Block isn't mandatory but it's quite efficient to cap it with a Duelist using a very large Thread of Hope and Versatile Combatant.

A note on the Precursor's Emblem - the one I'm using is very specific and will be very hard to find. However, you can play the build without the +1 PC / gain up to max frenzy Precursor's. You give up ~40M damage going from 11 max charges to 9, but that's still a 130M average hit.

TLDR: Supreme Grandstanding + Scold's Bridle + BFoT generates charges at a reasonable rate, enough for Discharge when paired with Inexorable and some sources of "instead gain up to maximum." This frees up your body armour slot to make room for The Admiral which, along with a Doryani's Prototype merc, multiplies the damage of the build by a factor of ~4.