The counterpart of Plugger for druids was soloing Mother Smolderweb in Lower Blackrock Spire at level 60 for your Wildheart boots.

One I used to do as a stealth challenge used to be in Lower Blackrock Spire obtaining both the Smolderweb and Worg Pup pet. You had to stealth in and snag the smolderweb eggs and the worg pup to get the pets. Now both have been changed to guaranteed drops. the true challenging part was to see if you could do it at level 55, the first level the quest became available.

The Suppression Rooms before Broodlord Lashlayer in BWD provide a fair challenge for rogue. I'm surprised it wasn't included in the article. To get to Broodlord Lashlayer one must go through several rooms with suppression devices - traps that give off an AoE aura which reduces movement/attack/casting speed by 80%. A rogue can of course disarm the traps. However, if you get too close to the traps the aura will break stealth, and you also have to be cautious to not agro any of the mobs scattered throughout the rooms. It takes a skilled rogue to chain disarm the traps leading to the Broodlord without breaking stealth.