Okay, I found that NPC Kreutz gives this knowledge for 10 energy

This is correct, the first knowledge can be achieved from Jeron via Kelcas, Leader of the Khurutos. You can just take the daily repeating version from Jeron to get scrolls without needing to forfeit, and you get some minor contribution xp while doing so (if you want to chip away at this, or forgot to forfeit).

This may be but it's really a hell figuring out how you get to that quest. My main has done every single quest possible in the game (certainly all those in calpheon anyway) and cannot get the knowledge from this character, I assume because I got through all the quests years ago and since they revamped the questlines so many times this quest was not available to him (though i DID do one where i had to beat Kelcas but it has a different name)

Knowledge available from NPCs should not be locked behind quests, lock it behind level maybe at most. But this is ridiculous. I'm trying to find out on a Drakania alt that has done all the story quests up to odylitta how to get to this quest and I can't. I can see anyway that at no point did I have to face this boss in the storyline quests... Are the quests really all the same with any class? The fact that some people did get it on some classes and not on others seems to suggest this. It's all so confusing.

Ok, i have found an alt that has completed this quest. So drakania, my most recent alt, didn't have this quest in all the main quests, my main, my oldest char, didn't have it either, but I found it in both my Dark knight and Zerker quests list (I havent checked all my alts). Zerker hasn't done the quest but DK has. So people, this is what you need to look for. Look at your main quests and see if you can find stomp heard around the world, whether you finished it or not. If you cant see it, you'll need to try a different class.