Killed Korvaak with a Pierce/Bleed Elementalist. This is my first pierce/bleed build, and I was pleasantly surprised by how well it worked.
It uses the Sharpshooter set, the Pierce conduit for Devouring Swarm, and Plunderer’s Talisman. The Sharpshooter set, Feral Hunger, and Plunderer’s Talisman all have significant passthrough chance, for a total of 70.5%.
The build worked without the conduit, but it was a noticeable damage increase when I was able to use it. The biggest change with the conduit was a surprise: it significantly increased sustain vs. large groups. Devouring Swarm leeches a lot, but before the conduit, I was doing about 400 vitality damage per tick, and after it was about 1200 piercing per tick.
This build hits hard, and devastates groups, but is also squishy, at least my current version. My character is deathless, so far, but I would not recommend it for hardcore, as it had several close calls in both the Kymon and the Korvaak fights, and I spent most of my time running away from both of them. The Korvaak fight was easier, mostly because I had plenty of space to run away in.
Gear upgrades and tweaks to the build would probably cure the squishiness problem. My DA and OA were both around 2100, and though Blast Shield saved my life several times in both the Kymon and Korvaak fights, I only have 9 points in it including +skills.
It deals the majority of its damage in pierce, not bleed. It does 5.7 times as much pierce as bleed from plain fire strike just looking at tooltip numbers, however, that doesn’t take into account the bleed from Feral Hunger, Rend, or Devouring Swarm. My best guess is that it does somewhere between 3 and 5 times as much pierce as bleed. I think it should count as both pierce and bleed for the chart, but that’s a judgement call.
Based on my experience with this build, I firmly believe that any pierce Demolitionist can be done with the Sharpshooter set, and probably also the Valdun set. Currently unfinished pierce Demolitionists are Pyromancer, Sorceress, and Defiler.