As you click each set of musical notes, you get a little message such as Blue musical notes dissipate into the atmosphere. You hear the C key. Remember the color of the FIRST note you clicked.
Play the note that corresponds to the first musical note you clicked to pop the name. The key will be the same color and will show the note as you hover over it.
The fight:
It is helpful to have the Threat List Window open (/togglethreatlistwindow) so you can quickly and accurately target the appropriate add.
The Organ Donor has a damage shield which stops most damage she receives. You win this by killing the right adds at the right time.
Pay attention to the order of the color of the notes that periodically spawn floating above the organ. From left to right, kill the dirge adds that match those notes (and only those adds, in that order, so fight in Singular Focus). This order is random for each spawn of the adds:
Once you have killed the correct dirges, the rest disappear and you can damage the The Organ Donor until she calls for an "Encooooooooore!" heralding the next wave of adds.
