Captain Madison can be a pain if his damage stacks get too high to heal through but I've rarely seen that since the first couple of days when people were learning. The Cactus boss in Qarn HM can be hard if the DPS get too distracted by the adds. The only add they need to burn before the boss to stop needles is the Guardia but a lot of people try to burn the adds then the boss because they think they have to. Had a couple of wipes from them messing around with the adds instead of focusing the boss when needle count starts. If done properly it's incredibly easy way more so than Captain Madison.