One piece of info concerning
Slave Pens. On heroic difficulty players could pick up the quest
The Mark of Vashj from Skar'this the Heretic. It was a bla-bla pre-quest for
The Cudgel of Kar'desh which upon completion would grant players the title "Champion of the Naaru". In patch 3.0.2 Blizzard replaced the quest with
The Cudgel of Kar'desh (different quest ID), which has no pre-quest. Hm, why?
This quest is no longer required to enter Serpentshrine Cavern and grants players nothing. It's only available to do those stupid people (like me) who did the bla-bla pre-quest, but dropped the original "The Cudgel of Kar'desh" pre-3.0.2. New players can't get any quests from Skar'this the Heretic. I was doing heroic Slave Pens with a friend, as we both want to finish Black Temple chain for
Blessed Medallion of Karabor. We thought that not getting proper attunement to SSC might not allow us to continue the chain. When we were near Skar'this the Heretic he couldn't pick up any quests, while I was still seeing new "The Cudgel of Kar'desh" (I've done pre-quest long ago).
Also comment at Wowhead says that GM confirmed the removal of "The Mark of Vashj" quest, so removing "The Cudgel of Kar'desh" from Slave Pens in AtlasQuest seems fair to me.