Level 120 - Congratulations on such an achievement! Unlike previous quests, the ones for level 120 are a little vague. Good luck!
All these quests require a minimum level of 120, and you must be a Cygnus Knight.
Chasing the Knight's Target
Involved: The familiar old light bulb over your head
Process: You know the drill by now. Click the lightbulb, accept, and find the NPC for the next quest.
Hunting the Zombies
Involved: [Jade], Forest of Dead Trees, [Coolie Zombie], [Black Scale - Ground], [Black Scale - Inventory]
Requires: Chasing the Knight's Target accepted
Process: Unlike previous quests, you do not need to visit Neinheart after the lightbulb quest appears. Instead, make a visit to El Nath, and look for Jade on the east side of town. She will give you the rather vague hint that the knight you are looking for was hunting zombies. Where can you find zombies? Way up in the El Nath dungeon, of course. Leave to the east side of town and keep going right and up until you encounter Coolie Zombies (I am not sure if Minor Zombies inside the mine work, but Coolie Zombies for sure do). You can also take the black VIP Cab on the east side of town to skip over some of the trip, or use a Dead Mine Scroll and backtrack a map or two to the zombies. Coolie Zombies should be easy to kill in one hit by now, but it may take a lot of kills though to find the item of interest - the Black Scale. For reference, I found about 125 Zombie's Lost Tooth before a Black Scale. Later, I found only one Black Scale in the process of finding 60 Zombie's Lost Gold Tooth. So I may have simply gotten lucky. As you can see in the pictures above though, the Black Scale is tradable, so if you're lucky, you may be able to find someone who already has one to buy from, or at the very least more easily get help from friends. Either way, once you have the scale, this quest is automatically considered completed and the next one becomes available.
Black Scale
Involved: Lightbulb!, Black Scale, [Spiruna's House - Map], [Spiruna's House - Entrance], [Spiruna]
Requires: Hunting the Zombies completed, Black Scale in possession
Process: After locating the Black Scale for the previous quest, yet another lightbulb will appear over your head. For the first time for Cygnus Knight quests, this one is from Spiruna! She simply wants you to take the Black Scale to her in Orbis. To locate her, go back to Orbis and take the middle height portal in town (right over the entrance to Orbis Tower). Then take the lower portal, and keep going down and right to Cloud Park IV. Once in Cloud Park IV, enter the house in the center on ground level and talk to Spiruna to complete this quest.
Dragon Outcasts
Involved: [Chief Tatamo], [Manon's Forest - Map], [Manon's Forest - Entrance], [Nix]
Requires: Black Scale completed
Process: Accept this quest from Chief Tatamo near the center of town in Leafre. Then, locate and talk to Nix, who can be found in Isolated Forest which can be accessed through either Manon's Forest or Griffey's Forest. See the maps in the Involved section for help.
The Stolen Egg
Involved: Nix, Griffey, Manon
Requires: Dragon Outcasts completed
Process: Leave the Isolated Forest through either side. One direction goes to Griffey's Forest, the other to Manon's Forest. You must find the boss monster that spawns in each one and defeat it. They are much harder than the level 110 skill bosses and only spawn once every six hours. You may need to check each channel or even wait in order to find one. I recommend bringing friends along as well. Once you have defeated each boss at least once, return to Nix.
The Cave of the Black Witch
Involved: [Nest of a Dead Dragon - Map], [Cave of Black Witches - Entrance], [Frightening Marble]
Process: Locate Nest of a Dead Dragon in Leafre (way out in the middle of nowhere by the skelegons) and enter the cave there. Talk to the Frightening Marble NPC inside to accept and finish this quest at the same time.
The Knight That Disappeared
Involved: Neinheart, Cave of Black Witches, [Fallen Knight]
Process: Accept this quest from Neinheart, then stock up on potions. You will be dealing with Darkness (non mages may want to bring eyedrops from the potion store in Ereve to counter the reduction of accuracy) and Zombify (all classes may want to bring potions that recover double to counter the 50% decrease in potion recovery). Chances are you will die a few times too. Makes you glad you don't need to level any more, huh? After preparations are done, visit the Cave of Black Witches again and talk to the Fallen Knight NPC there that you "missed" last time (actually, he wasn't even there!).
The Curse of the Black Witch
Involved: Shinsoo, [Black Witch]
Process: Talk to Shinsoo, then head west a short way and talk to the Black Witch. Decline when asked to (accepting won't get you anywhere) and then get ready for a fight! Kill the Black Witch, who will turn into a boss monster, and then talk to Shinsoo again. Then leave the map through the portal on the left.
----Animations
Watch those skill animations, or you'll end up dead!
Bluish white pillar of light in front of her: Moderately dangerous. Deals 3K damage and knocks you across the screen.
Black circle on top of her: Mildly annoying. Inflicts Zombify at a fairly low rate. Potions temporarily recover 50% of what they normally do on success.
Blue circles rising around her while her mouth is open: Mildly annoying. Inflicts Darkness at a fairly low rate. Temporarily severely reduces accuracy on success.
Blue circles rising around her while her mouth is closed: Incredibly dangerous. Casts Damage Reflect on herself at a 100% rate. All damage dealt to her is returned to you. Don't attack until the purple icon is gone!
----Notes
• She has quite a lot of hit points and a very high knockback amount (11K damage will not knock her back).
• Summons can safely hit her even with damage reflect on, although it only does 1 damage. Can be useful for identifying whether it is on or not.
• Damage reflect is only cast after 50% of her hit points are gone. Until the health bar no longer passes the right edge of the timer, you're safe.
• The second step from the top of the structure on the left is outside her range, but leaves her within range of some player attacks. This can possibly be used to your advantage.
----Correction: As of patch version 0.80, you can no longer jump up onto the stairs in the Black Witch's map in GMS (although you can jump onto the stairs in the regular version of the map). Sorry everyone, you'll just have to take the hits.
Note on Echo of Hero: In case you haven't had a skill with a long cooldown time before, Echo of Hero's two hour cooldown timer will not progress unless you are actually online. Logging out pauses it. =/
Stolen from:
http://www.basilmarket.com/forum/1150348/0//Cygnus_Knight_Quest_Guide.html#Ereve10