Scourge Invasion

The Scourge Invasion was a world event in patch 1.11 that heralded the opening of Naxxramas, the citadel of the dreaded Kel'Thuzad. It was reintroduced into the game in patch 3.0.2 partway through the Zombie Infestation event, in preparation for Wrath of the Lich King, and tuned for the new level cap which players had achieved (70), occurring after Hallow's End. It is thus the only non-seasonal world event to have ever been repeated.

Death Rising, the pre-event for Shadowlands as the Scourge are marauding across Azeroth, was heavily inspired by the Scourge Invasion.

Official description
During the invasion, several regions of Azeroth came under attack by Scourge forces. Members of the Argent Dawn organized a worldwide counter to the Scourge invasion, keeping an eye out for any necropolis sightings and passing on their information to all adventurers willing to aid them in their struggle.

With each victory against the Scourge, the defense grows stronger. As more and more invasion attempts are beaten back by the defenders, the Argent Dawn will be able to bestow increasingly more powerful blessings upon those fighting the invaders. If the mortal races focus on clearing the Scourge camps all over the world that have sprung up beneath each necropolis, perhaps the invasion can effectively be halted or even repelled. Those who wish to take up arms against the undead invaders should speak with a representative of the Argent Dawn to learn what regions need help and how the defense is holding up.

There are also reports of Scourge agents showing up in Stratholme, the Scholomance, Dire Maul, the Scarlet Monastery, Shadowfang Keep and the Razorfen Downs. Whatever their purpose there may be, the world will surely be better off if they are destroyed before their evil plans are fulfilled.

A necropolis has appeared outside Stormwind and Undercity, and soon the assault on these capitals will launch in full force. Skeletal shock troops are standing by to commence the attack, led by abominations and gruesome undead officers. The city guard will need all the help they can get once the Scourge unleashes its wrath on the cities. The Argent Dawn has already heeded their desperate call for help, setting up camps inside the besieged cities and rallying the defense against the encroaching darkness.

Necropolis invasions, Necrotic Runes, and the Shards
During the Scourge Invasion, numerous high-level zones are under attack by one or two flying necropoli each. The zones under attack have purple skull markers on the continent-level maps. The zones that get attacked are Eastern Plaguelands, Burning Steppes, Blasted Lands, Tanaris, Azshara, and Winterspring. See a collection of maps showing possible spawnpoints for scourge forces

NPCs near Argent Dawn tents in the major cities will note where the necropoleis are attacking, and how many are in each zone. There are also necropoleis over the capitals. The ones over the major cities seem to be permanent but they only spawn low level scourge for the introductory quest. If you look on the world map, areas under attack (excluding capital cities) will be marked with a purple skull.

Assaulting the Necropolis
The necropoli are accompanied by Necrotic Shards, which are visible on the ground near each of the flying citadels. These shards are always surrounded by a large number of undead. The undead are non-elite and grant 5 Argent Dawn reputation until the end of, unlike normal undead. They yield if slain while having the  equipped.

The Shards near the undead are weakened as the undead are killed. When the strength of the shard reaches zero, four Cultist Engineers will appear and start to heal it. Each of these engineers can be "disrupted" through the use of eight Necrotic Runes. The Acolyte will then convert into a Shadow of Doom, which is a tough 70 elite mob. Upon its defeat, the Shadow of Doom will yield a, 50 reputation with the Argent Dawn, 30 Necrotic Runes, and has a chance to drop a chest piece of the Undead Slaying set.

Destroying all four Shadows of Doom will destroy the Necrotic Shard, heal nearby players for 10,000, grant them a powerful buff, and stop new Scourge from spawning there (at least for a short time).

Destroying all the Necrotic Shards attached to a necropolis will destroy the necropolis. Destroying all the necropoli in a zone will cause that zone to no longer be under attack. The Scourge will eventually deploy more necropolises however, so clearing a zone does not mean it is safe forever.

Marks of the Dawn
After a certain number of battles have been won on a server, additional rewards are available. After the battles have been completed, a new NPC will spawn at Lights Hope Chapel and in your faction capital and will hand three of the item out for free!

Necrotic Rune turn-ins
The undead have a chance to drop a Necrotic Rune. Commander Thomas Helleran at Light's Hope Chapel wants ten of these runes to complete the quest Under the Shadow; after completing Under the Shadow the remainder can also be turned in to the Argent Quartermaster at Light's Hope Chapel or in camps in your faction capital city for various rewards:

Mob drops
In the original Scourge Invasion, three rare spawns appear at each of the Shards (Bone Witch, Lumbering Horror and Spirit of the Damned), which drop two to three Necrotic Runes as well as the bracers of the Undead Slaying set. Like most rare spawns, they are not elite but are slightly higher level. These spawns appear roughly every fifteen minutes after engagement of Scourge in the area, and despawn about fifteen minutes later.

In the second Scourge Invasion, the rare spawns are level 71, and instead drop the pants for the new Blessed Undead Slaying sets with 100% chance of drop. These can be easily taken down if fought without any adds; a level 68 tank and another DPS character or healer will easily make quick work of these rares.

Letters from the Scourge
Non-elite undead around the Necrotic Shards will occasionally drop letters. There are six total, each of which starts a turn-in quest at the Keeper of the Rolls in Light's Hope Chapel for a small reward. Once the quest is started, the letters may be read. They contain well-written bits of lore, mainly related to the events in Warcraft III. These letters appear in both versions of the Scourge Invasion.

A week after turning in a letter you will receive through the mail a message from the Keeper indicating a NPC that is mentioned in the original (quest) letter. This does not start a quest. The NPCs indicated become vendors that will sell you (2934 mana over 30 secs) and  (2148 health over 30 secs). There is no other reward, and the lemonade and bread are functionally equivalent to normal level 45 vendor food and drink, though while consuming them an animation of a cartoon heart is displayed above your character and a short, tinging sound will repeat. These vendors continue to sell these items after the Scourge Invasion ends. There is one vendor in each faction capital city as well as Booty Bay, Eastern Plaguelands, and Silithus.

Capital city invasions
Aside from the necropolis events outdoors, Scourge mobs will occasionally appear in Stormwind and Undercity. They spawn seemingly at random, causing city NPCs to yell for help. The most common are Flameshockers, level 55 mobs (level 63 elite mobs during the second Invasion) which do not hit very hard, but have a very large amount of health points. The city NPCs are capable of killing the Flameshockers on their own, but if a player or group chooses to tag them, they will receive 5 Argent Dawn rep (at Honored). Flameshockers can drop Necrotic Runes.

There are also groups of tougher elite mobs (Pallid Horror) that periodically spawn in Stormwind and Undercity and attempt to get to the city leader, causing him/her to yell that he/she is under attack. (These do not pose an actual threat to racial leaders, they are easily able to defeat the creatures if they manage to reach them.) When all the mobs are defeated, the city leader will yell that they are safe, and a dead Necrotic Shard will spawn. The shard will give a quest to talk to a NPC at Light's Hope Chapel. Any player can receive this quest, even if they did not tag the mobs that spawned the shard.

All the mobs that spawn inside cities are yellow (passive) and do not attack players who haven't attacked them first. They also appear not to attack vital NPCs such as bankers and vendors. So, it would seem players who aren't interested in the city events are not threatened by them in any way, and can simply ignore them and go about their business.

NPCs

 * Stormwind Elite Guard

New bosses
There are also reports of Scourge agents showing up in Stratholme, Scholomance, Dire Maul, the Scarlet Monastery, Shadowfang Keep, Razorfen Downs, and Karazhan. These new boss mobs can be identified by the glowing purple aura they have which is similar to those of the invading Scourge outside the instances.

Tenris Mirkblood‎
, a San'layn, can be found above Attumen the Huntsman's room in the kitchen. He is the objective of Chamber of Secrets. Introduced with the second Invasion.

Balzaphon
is a lich who formerly patrolled the fountain courtyard to the left of the service entrance in Stratholme. Balzaphon uses many frost based abilities. He has since patch 3.0.2 been moved from his patrol route and now stands in a corner northeast of the fountain.

Lord Blackwood
resides in Scholomance. He is a large skeleton who attacks with both ranged bow attacks and heavy melee attacks.

Revanchion
, a wraith, wanders the hallway behind Tendris Warpwood in Dire Maul.

Scorn
The lich appears in the graveyard portion of the The Scarlet Monastery once Bloodmage Thalnos is defeated.

Sever
The abomination appears in Shadowfang Keep along the corridor that runs parallel to the Great Hall and Kitchen. He is arguably the hardest boss in the instance.

Lady Falther'ess
, a banshee, and can be found in the slaughter pens area of Razorfen Downs.

Quests
The following is a list of quests available during the second Invasion.


 * Investigate the Scourge of Stormwind
 * Investigate the Scourge of Darnassus
 * Investigate the Scourge of Exodar
 * Investigate the Scourge of Ironforge
 * Cracked Necrotic Crystal (quest)
 * Investigate the Scourge of the Undercity
 * Investigate the Scourge of Orgrimmar
 * Investigate the Scourge of Silvermoon
 * Investigate the Scourge of Thunder Bluff
 * Faint Necrotic Crystal (quest)
 * The Keeper's Call
 * Light's Hope Chapel (quest)
 * Under the Shadow
 * Shadows of Doom
 * Chamber of Secrets

The following quests start from rare drops off the non-elite Scourge near any crystal.
 * Letter from the Front (quest)
 * Page from the Front
 * Envelope from the Front
 * Note from the Front
 * Document from the Front
 * Missive from the Front

In Shattrath, on the Terrace of Light, members of the Church of the Holy Light for the Alliance and the Royal Apothecary Society for the Horde work to combat the Plague of Undeath and the floating necropolises.

The second Scourge Invasion
The second Scourge Invasion began partway through the Zombie Infestation world event, shortly after patch 3.0.2, immediately preceding the release of Wrath of the Lich King.

The second Invasion largely mirrored the first Invasion, albeit with the addition of Tenris Mirkblood and numerous changes to the available quests and rewards. However, the second Invasion also featured additional events beginning November 10, 2008. Special events, described below, began to play out in each faction's capital, while the forces of the scourge began attacking Stormwind Harbor and Orgrimmar's Valley of Honor every thirty minutes, with actively hostile 72 elite and 71 elite  abominations.

Stormwind

 * Herald of the Lich King yells: FOOLS OF STORMWIND! HEAR ME, NAIVE CHILDREN OF THE ALLIANCE! TREMBLE AND KNOW YOUR DOOM, FOR THE LICH KING'S GAZE IS FIXED UPON YOU!
 * King Varian Wrynn yells: See to your arms! We must protect the harbor, or the Alliance's assault on Northrend will be halted before it can even begin!

Fifteen minutes later:
 * King Varian Wrynn yells: Enough! I will not stand for this!
 * King Varian Wrynn yells: I'll kill every last one of your pawns, Lich King!
 * King Varian Wrynn yells: Take your flying fortresses back to Northrend, before I crush them with my bare hands!
 * The King goes berserk, jumping hither and thither around the Harbor, one-shotting any hostiles.
 * Herald of the Lich King yells: ARGH! THIS SMALL VICTORY WILL AVAIL YOU NOTHING! COME! COME TO NORTHREND. MY MINIONS ARE WAITING, AND THEY ARE HUNGRY....

Stormwind: comic version

 * Dwarven cannoneer says: Fightn' those lifeless monsters'll be a nightmare, King Varian, an' no mistakin' it.
 * King Varian Wrynn says: The sooner we take this war to the Scourge in Northrend, the safer our people here will be.
 * King Varian Wrynn says: Fear not, Hovik! We can win this war!
 * Hovik says: I… I know, sire. It's just… This fog!
 * Prince Anduin Wrynn says: This fog's unnatural!
 * Highlord Bolvar Fordragon says: And that stench! Where--?
 * Prince Anduin Wrynn says: By the Light! What is that--?!
 * Herald of the Lich King yells: TODAY WE WILL FORGE A NEW ALLIANCE—FOR TODAY YOU WILL FIGHT AND DIE! AND YOUR BODIES WILL RISE TO JOIN THE LICH KING'S UNDEAD ARMIES! ALL HAIL THE LICH KING… SOON TO BE KING OF STORMWIND… AND ALL OF AZEROTH!
 * King Varian Wrynn says: Warriors of Stormwind, draw your weapons and follow me! Today we conquer death itself! Bolvar! Get Anduin to safety!
 * Prince Anduin Wrynn says: Father! No! I'm not afraid--!
 * King Varian Wrynn says: No one questions your bravery, Anduin! But a touch of that green slime and you become one of them. Then where would our people be?
 * Highlord Bolvar Fordragon says: Varian's right, Anduin. You both can't be at risk! Your presence here distracts your father. He'll need his wits to fight this horror.
 * King Varian Wrynn says: Stormwind attack! Send the Lich King's undead army to the Twisting Nether! Magi, shield the city! Force that flying fortress seaward!
 * Stormwind Archmage says: Seaward sire?
 * King Varian Wrynn says: Do it! Just avoid our fleet!
 * Prince Anduin Wrynn says: Father! Behind you--! Anduin throws a dagger and decapitates a Scourge Father never saw that Scourge! He could have died!
 * Highlord Bolvar Fordragon says: Up in the tower Anduin, quickly! You can use your bow and arrows to protect him!
 * Prince Anduin Wrynn says: Father glories in battle, Bolvar! But I… I know we need to fight… But I just long for peace!

After King Magni's flying machine reinforcements destroy the necropolis
 * Herald of the Lich King yells: THIS SMALL VICTORY WILL AVAIL YOU NOTHING! COME! COME TO NORTHREND. MY MINIONS ARE WAITING, AND THEY ARE HUNGRY....
 * King Varian Wrynn says: Then we will feed them a diet of steel! For soon, we take this war to the Lich King's frozen shore!

After the battle with the Scourge
 * Highlord Bolvar Fordragon says: The Valiance Expedition sets sail for Northrend on the evening tide, sire.
 * King Varian Wrynn says: There is no one I trust more to create the base at Angrathar, my friend.
 * Highlord Bolvar Fordragon says: In the shadow of Icecrown! That will tweak the Lich King's nose, Varian… And pay him back for daring to send a necropolis against Stormwind!
 * Prince Anduin Wrynn says: I'm going to miss you Bolvar! Be careful!
 * Highlord Bolvar Fordragon says: I'll do my best!
 * King Varian Wrynn says: You are more brother to me than even blood! Keep safe! Stormwind needs you!
 * Prince Anduin Wrynn says: I wish Bolvar didn't have to go. I wish there were no enemies or battles… But you aren't like that, are you, father? You're sorry not to be going with Bolvar. You love to fight. Father, do you think there is something wrong with me that I do not?
 * King Varian Wrynn says: You're a valiant lad Anduin. And when you have to fight you acquit yourself bravely. With honor. That is enough. I do not thirst for war as some men do. But… its true that I feel most alive in the midst of battle. Maybe that means there's something wrong with me… Though that's just as well considering the present circumstances. A great and terrible war is coming. When we win and the Lich King has been defeated… Then let us hope that your time, a time of peace and healing, will begin. When that day comes, you will be greater than I.

Orgrimmar

 * Garrosh Hellscream says: Thrall...Warchief...your armies await your command. Let me lead them to Northrend to remove this undead menace!
 * Lady Sylvanas Windrunner says: Yes, Thrall. The time has come to kill Arthas. You can take my grand apothecary with you. His knowledge will be invaluable against whatever the Scourge will throw at you.
 * Grand Apothecary Putress says: It would be an honor, Dark Lady.
 * Thrall says: What say you, Saurfang?
 * High Overlord Saurfang says: Warchief, it is clear that Northrend represents the gravest threat to our people, and that we must act against it.
 * Thrall says: My soul burns for revenge, but the elements tell me to think clearly. The Lich King is a ruthless opponent...one who must be handled carefully.
 * Thrall says: We will send scouts to assess the situation. I will also convene with the Lady Proudmoore and see what plans the Alliance has.
 * Garrosh Hellscream says: Gragh! I cannot take this! While you talk and deliberate, our enemies grow stronger! Were it my choice, I would have put all our available forces onto that frozen rock and conquered it for the Horde!
 * Thrall says: If this is a trap, it is one I will not blindly walk into! Do not make the same mistakes as your father, Garrosh!
 * Garrosh Hellscream says: After all that he did for YOU and YOUR people? MAK'GORA!
 * Thrall says: You challenge me boy? I don't have time for this....
 * Garrosh Hellscream says: So you refuse? Is the son of Durotan a coward?
 * Thrall says: Inside!
 * Thrall and Garrosh enter the Orgrimmar Arena.
 * Thrall says: Let's finish this quickly.
 * Garrosh Hellscream says: Your duties as Warchief can wait. For now... we fight!
 * After the fight...
 * Thrall yells: GYAH!
 * Garrosh Hellscream yells: Hah! So, son of Durotan, what--
 * Herald of the Lich King yells: PUPS OF ORGRIMMAR! HEAR ME, BRASH UPSTARTS OF THE HORDE! TREMBLE, AND KNOW YOUR DOOM, FOR THE LICH KING'S GAZE IS FIXED UPON YOU!
 * High Overlord Saurfang yells: Warchief! Scourge forces are attacking Orgrimmar!
 * Thrall says: We will finish this later, son of Grom.

Later:
 * Herald of the Lich King yells: ARGH! THIS SMALL VICTORY WILL AVAIL YOU NOTHING! COME! COME TO NORTHREND. MY MINIONS ARE WAITING, AND THEY ARE HUNGRY....
 * Garrosh Hellscream says: Well, Warchief? What say you now? Will you send me to Northrend?
 * Thrall says: Saurfang...
 * High Overlord Saurfang says: Yes, Warchief?
 * Thrall says: Marshal our forces. Contact our goblin shipwrights. The Horde prepares for war!
 * High Overlord Saurfang says: As you command Warchief!
 * Lady Sylvanas Windrunner says: Excellent...most excellent.

Orgrimmar: comic version

 * Garrosh Hellscream says: By your “statecraft” you turn the orcs into weaklings, warchief! We should conquer the humans, who are as nothing then send our forces to Northrend to crush the Lich King and his undead army! The Horde should rule all of Azeroth!
 * Rehgar Earthfury whispers: Garrosh is close to challenging your leadership Thrall.
 * Thrall whispers: I fear you are right Rehgar. Twould be best to force his hand before support for his ideas grows!
 * Thrall says: The humans are no threat to us. While the Lich King is a wily opponent. I will not walk blindly into his trap! Nor will I make the same mistakes as your father!
 * Garrosh Hellscream says: You insult my father thus? After all Grom Hellscream did for you and your people? MAK'GORA!
 * Thrall says: A challenge, boy? Inside then! We finish this quickly--
 * Thrall and Garrosh enter the Orgrimmar Arena.
 * During the fight...
 * High Overlord Saurfang yells: Warchief! Scourge forces are attacking Orgrimmar!
 * Thrall says: We will finish this later, Garrosh! Thrall casts Chain Lightning on Garrosh But for now, the issue is decided! We spend our fury on the Scourge!
 * Herald of the Lich King yells: HERE ME, ORCS OF ORGRIMMAR! BRASH UPSTARTS OF THE HORDE! TREMBLE, AND KNOW YOUR DOOM, FOR THE LICH KING'S GAZE IS FIXED UPON YOU!
 * Rehgar Earthfury says: The Scourge must have been behind the attack at Theramore! Had you been killed, we orcs would have been in disarray before the Lich King's undead army!
 * Thrall says: Whoever's plot it was, it failed! We face the Scourge united…
 * Rehgar Earthfury says: ...And victory will be ours!
 * Rehgar Earthfury says: The Lich King's necropolis is almost upon us Thrall.
 * Thrall says: It cannot be allowed to destroy what we have built here! Let the earth rise up in anger! Let fire rain from the heavens! Thrall conjures a lightning storm that hits the necropolis Let the wind carry our defiance to the Lich King's minions…! Thrall casts a sandstorm and blows the necropolis away …For neither Lich King nor Scourge are welcome here!
 * Herald of the Lich King yells: THIS SMALL VICTORY WILL AVAIL YOU NOTHING! COME! COME TO NORTHREND. MY MINIONS ARE WAITING, AND THEY ARE HUNGRY!
 * Thrall says: Tell your master we accept his invitation! Marshal our forces Saurfang! Contact the goblin shipwrights! The Horde prepares for war!