During the last fight in the instance if you grab the chancel for the Siren of Orr mastery it will interfere with the ability to use Counter Magic. Even though the Counter Magic icon will show up in the Special Action slot activating does behave as expected. Normally when using Counter Magic it will remove all the conditions that was applied but if you have the chancel it will not do that. Once the Dirge is used Counter Magic goes back to working normally.