I might be blind, I got this achievement weeks ago, you get it when you complete the "Clear the Curtain Wall" mini-quest in Thresinet's Den but I can't find it in any of the categories in my achievement window and it's not showing up on eq2u either? Curious if anyone else can see it?
It will be displayed in Quests > Altar of Malice, but only if completed as it's a hidden achievement. (It's not hidden anymore, though, since you spilled the beans, TrulyVexed!)
Doh! Guess this just confirms that I'm blind! (something the missus regularly tells me when I'm looking in cupboards for something) Btw.. I'm loving the amount of hidden achievements in the heroic zones, whenever I've pugged and pointed out some of the less obvious ones people have been really surprised (Caldera especially). I had the whole guild convinced that I was playing a prank on them when I got a guild group them to jump off the waterfall in Bilgewater Falls.. much fun was had!
