You must stay on BLM while investigating the first two ???s. At one point the magic doll will tell you to use your "BLACK POWER," and you will need to use Manafont. You can change to any job afterwards.
The first ??? is at (H-7) of the first map of the Toraimarai Canal, fairly close to the Horutoto entrance. These are not the sparkling ???'s. Check it and get a cutscene where the doll absorbs the magic. To get the cutscene, you must be on the same side of the gate as the ???- you can receive text from either side, but only one side will give the cutscene.
The second ??? is at (I-9) on the same map, on the west side of that gate. Check the ??? for a cutscene, use Manafont, and check the ??? once again for a second cutscene. (This is the only portion of the quest that requires you to be BLM. You may leave the canal after this and return as another job to fight the NM.)
Head to the third ??? at (J-8). When you examine it, the NM Magic Sludge will spawn.
There are two ??? at the (J-8) spawn point less than a half-inch apart. If you receive the message "There is nothing out of the ordinary here" and you successfully eradicated the first two magic stagnations, you may be trying the wrong ??? and simply need to look carefully at which one you have selected.
It is highly recommended that you clear the room of any regular mobs before popping the NM and then pulling the NM into the hallway to avoid aggro once the mobs respawn.
The NM is like all other elementals in that it's highly resistant to physical attacks, but is also resistant to magic. Some ways to get around the damage resistances are:
You also may choose to use some Poison Potions if you want to reduce the danger of the Sleepga it can cast.
You do not have to kill this once per Black Mage; simply clear the area and have each BLM pop the Magic Sludge with sneak letting the elemental depop each time. Then when the last BLM pops kill Magic Sludge then have all Blms examine the ??? for the CS. Meaning you only have to fight once. It takes 3 minutes to depop, and you must wait 3 minutes after that to repop it.
If you wipe while trying to kill the NM, simply raise up, wait for full heal, and pop the ??? again. You are not required to go and check the other two ???'s again before repopping Magic Sludge. You do not have to redo the first two ??? if you have to home point.
You can skip his cutscene by warping out or exiting through the Priming Gate into Windurst Walls. You can exit through it even if you lack the Rhinostery Certificate to use it as an entrance. You will still get your hat, but cannot proceed with the remaining cutscenes.
(Optional) Go to Heavens Tower and talk to Kupipi behind the reception desk near the Starway Stairway door for some cute dialog about fame.
The cause of the star trees' poor growth seems to lie in the Toraimarai Canal. First, bring some silk cloth to Professor Koru-Moru so he can improve his magic doll. Then take the magic doll into the Toraimarai Canal to carry out an inspection.
SPOILER WARNING: Click here for additional details about this story line.