And yes, it was more Hellgate: London today. I entered the one zone I had the essences to unlock, and it had the same underground hallway tileset as some of the ‘passageway’ zones, but with central chambers added. Not really much of interest there though, as the actual general was yet one more zone away. That zone had the same ‘hell plains’ setting as the final boss fight, and I found the general way down in the SE corner. I actually died once to him as he does a ton of damage with a teleporting attack, but otherwise I was able to gradually wear him down and keep myself just barely healed up.
After a bit more farming I had enough essences for another general, and it went much the same way, except that the general’s zone used the Mind of 314/Exospecter tileset. He was a pushover though; unlike the giant first general this one was normal sized and mixed in with a bunch of other monsters and I didn’t even realize I’d beaten him until finding his head in the middle of the pile of loot.
I still need three or four more of each of the remaining essences though, so they’re not being dropped at an equal rate. I did a couple more Temple Station quests, but the enemies are getting way too high level too quickly, so more grinding is going to be needed. I guess I can get back to farming Shulgoth for the achievement, at least…
I also started a Marksman and played him until level 7. It’s not really a lot different than the engineer in the early game though, so I’m not sure if I’ll bother with him much further.