1. Alliance Remnants Campaign: "The duty of the Militia"
Darius, a former captain of Lordaeron's civilian militia, and his family are deceived by members of the cult of the dammned, under the orders of Kel'Thuzad, and taken to a prisoner camp where his family and friends are transformed into undead. Darius escapes the camp with a few other prisoners, swearing vengeance against the scourge. During the campaign, the player incarnates Darius, who becomes the leader of a group of human survivors. Darius and his group travels to the ruins of Dalaran, where he finds a group of elf and human mages and priests who join forces with him. After Dalaran, Darius travels to Gilneas, where he help to defend the nation against the forsaken undead of Sylvannas. Darius' troops get to kill Varimathras in the battle, but Gilneas falls anyway, so Darius and his group take a few ships and escape to Kul Tiras, where he pledge allegiance to Tandred Proudmoore, who orders Darius to take his group and the ships he took from Gilneas and travel to Ironforge to discover what happened with the dwarves. In his travel to Ironforge, Darius finds demons and lately help the dwarves protect Ironforge. The king of Ironforge agree to help Kul Tiras fight the scourge. In the end, Kul Tiras sign an alliance with Sylvannas Windrunner and her forsaken to fight against Kel'Thuzad. While Sylvannas and Tandred fight the scourge, Darius infiltrates Naxxramas with his group and slays Kel'Thuzad. When Sylvannas get notice that the lich is dead, she betrays Kul Tiras and kills Tandred. Then she reveals that she got Ner'Zhul's spellbook from an "unexpected ally" and transforms Darius into one of her forsaken "so he can fill the place left by the weak Varimathras".
2. Forsaken Campaign: "The Black Queen of the East"
The corrupted Darius leads the forsaken to the leaderless nation of Kul Tiras and conquer it in the name of the Banshee Queen, then uses Kul Tiras' fleet to travel to the south, where he fight against the dwarves and conquer Ironforge. After the conquest of Ironforge, Darius discovers that the demons have stablished a base in the ruins of Stormwind. Darius leads the forsaken to Stormwind, where he siege the city. In the end, Sylvannas and Illidan appear and kill the demon lord in charge of the base. It's revealed that the one who gave Sylvannas the Ner'Zhul's spellbook is Illidan, so she would gain some of the same powers af the Lich King in exchange for her help to destroy the frozen throne and Arthas. Sylvannas changes her title from "The Black Lady" and "The Banshee Queen" to "The Black Queen".
3. Night Elf Campaign: "Purification"
The campaign starts with Malfurion trying to purify Felwood, where he discovers that the demonic presence in the zone has decreased, but the undead activity has increased. Finally, Malfurion discovers that Anub'Arak has been searching for something and track him to a cave where the druid discovers that the former nerubian king have been trying to extract the power of the tree of life from its roots. Anub'Arak informs Malfurion that even the roots of Nordrasill are dead and escapes from him. Malfurion reunites with Tyrande and fight against the scourge, to later discover that Anub'Arak is leading a huge army from the northern coast of Kalimdor to mount Hyjal. Lady Vashj appears suddenly, offering her help to Tyrande and Malfurion, and giving back Maiev as a sign of good will. With the help of Vashj and the Naga, Tyrande, Malfurion and Maiev defend Mount Hyjal and Anub'Arak retreats to Northrend. Vashj persuade the night elven leaders to help Illidan and Sylvannas in their quest to kill the Lich King.
4. Syndicate of the Outland Campaign: "Fall of Northrend"
The player controls a weakened Illidan that must start again from level 1 since part of his soul have been absorbed by the Forstmourne. Also, since he failed his mission, the Burning Legion is now his enemy and wants to kill him. While Vashj is helping the night elves, Illidan leaves Akama in charge of the Outlands while he leads Kael'Thas and an army of elite warriors and warlocks through the same portal that Ner'Zhul tried to escape the Outlands. From there, Illidan leads his expedition through another portal to the Eredar homeworld, Argus, where he sacrifices Kael'Thas in a blood ritual to resurrect the physichal body of Ner'Zhul and return his soul to said body. Illidan slains the resurrected Ner'Zhul inmediately, thus stripping the Lich King from half of his power. After that, Illidan return to the Outlands, followed by an army of demons. Illidan orders Akama the impossible mission of defending the Outlands against the burning legion while he travels to Azeroth. In Azeroth, While the night elves assault northrend from the west, the forsaken from the east and the naga from the south, Illidan takes a combined force of draenei, blood elves and naga through Azjol-Nerub, where he kills Anub'Arak. After that, he arrives Icecrown Glacier, where he assaults the frozen throne and fight Arthas once again, being victorious this time. While dying, the Lich King laughs while saying that "There'll always be a sovereign ruling the kingdom of the dead". Kil'Jaeden appears before Illidan and informs him that Akama is dead and the outlands are part of the Burning Legion once again. He also informs Illidan that the Lich King and Medivh were the only two powers able to interfere in their attempts to access Azeroth, and since Illidan killed the Lich King dimensional rifts were starting to appear all around Azeroth, allowing the demons to enter. Illidan accepts to help Kil'Jaeden conquer Azeroth with the condition that the Night Elves, and specially Tyrande, are spared. Kil'Jaeden accepts Illidan condition, but Illidan confess to Lady Vashj that he just want to find the opportunity to kill Kil'Jaeden.
5. Orcish Campaign: "Sunset of the Spirits"
The wind gives to Thrall the news that the Forzen Throne has fallen, but after that there're no more news from any spirit. The player incarnates a Thrall with strength and leadership, but without shamanistic power, having to travel through Durotar alone visiting places of high spiritual importance, only to find that they've been tainted by demons spawning from dimensional rifts. Thrall fight the demons and clean the spiritual places from the demonic presence, but there's still no response from the spirits. Abandoned by the spirits, some orcs drink the demonic blood and Thrall have to fight once again against the fel orcs. The number of rifts increases and Thrall send a message to Theramore calling for help. In the end, Thrall have to defend Orgrimmar against the waves of demons spawing from multiple rifts until Jaina arrives with reinforcements and wizards able to close the rifts. Before the last rift is closed, Thrall discovers that it leads to the Outlands, and decides to cross it with a small force, leaving Jaina orders to close it just partially and seal it completely after a month if he hasn't returned. Once in the outlands, Thrall travels to Nagrand, where he searchs for the origins of the shamanistic culture. His search leads him to the ruins of the first orc capitol, where he enters in comunion with the spirit of Draenor, who explains to him that the only reason for the spirits of Azeroth to escape in fear would be the arrival of the only living beign that could inspire fear in any spirit: The demon lord Sargeras. The spirit of Draenor accepts to help Thrall fight the burning legion in Azeroth since he had a personal grudge against them for the destruction of his world. Thrall returns to Azeroth bringing with him the spirit of Draenor, who convinces the spirits of Azeroth to return and fight again along with the orcs.
6. Demon Campaign: "The return of the Master"
The player incarnates Lord Rhoggeir, a powerful and promising but still young demon lord. While Kil'Jaeden leads the assault to Kalimdor and Illidan leads the assault to the Eastern Kingdoms, Kil'Jaeden orders Lord Rhoggeir to travel through the Eastern Kingdoms, where he fights but not kill Darius, and the Night Elven territory, where he fights Tyrande and Malfurion and kills Maiev, and recover the pieces of the broken eye of Sargeras. After that, Lord Rhoggeir must travel to the Tomb of Sargeras, where he must put together the pieces of the Eye of Sargeras and get back its power bathing the artifact in the blood of Sargeras, wich is in a pool in the lowerest of the levels of the tomb, guarded by demons who driked said blood and have become much more powerful at the cost of their sanity. After defeating the guards and bathing the eye in the blood, Lord Rhoggeir must travel to the Maelstrom, where Lady Vashj tries to stop him. After the defeat of Lady Vashj's elite guards, Illidan denies any relation with the Naga's actions. Lord Rhoggeir uses the Eye of Sargeras in the middle of the Maelstrom and starts a ritual. Lady Vashj tries to stop it while Lord Rhoggeir must defend the Eye. After the ritual is completed, Lord Rhoggeir slays Lady Vashj. The Maelstrom suddenly stops and in its middle appears a vortex that absorbs the Eye of Sargeras and slowly starts to increase in size.
7. Theramorian Campaign: "The fate of Azeroth"
Lady Jaina Proudmoore orders General Rein Goodwood to investigate the origin of the dimensional rifts while she and her most powerful wizards close the rifts that appears in the horde and alliance's territory. Goodwood finds a large demon base in the south-western coasts of Kalimdor and proceed to attack it. Goodwood wins the battle easily only to discover that the rifts and the demon bases were just a distraction to something much bigger. Goodwood informs Lady Jaina and Medivh appears suddenly to confirm that the demons are trying to give back to Sargeras his Physichal form using the power of the Well of Eternity for that purpose and the Eye of Sargeras as a catalyst, and that the result will appear directly in Azeroth, meaning the fall of the world. Medivh tells Jaina that if he can enter the vortex that is taking the place of the Maelstrom, he can stop the summoning, but that if they intend to do so, they will need the power of the horde, alliance and night elves united again to break through the demon forces defending the Well of Eternity. Jaina and Thrall march to the Well of Eternity while Goodwood is sent to inform the night elves of the plan. When Goodwood arrives to the northern Kalimdor, he discovers that most of the night elven territory have been taken by the demons. When he finally find the elven survivors, he's informed that Malfurion have been badly injured trying to stop Kil'Jaeden, who entered Azeroth through the Well of Eternity. Goodwood decides to fight along with the night elves to kill Kil'Jaeden. During the battle against Kil'Jaeden's forces, the remnants of the blood elves, the draenei and the naga appears in the battlefield to help the night elves, refusing to give them a reason to do so. Even through the allied forces manage to keep the demon forces away, Kil'Jaeden suddenly appears in the battlefield, and the blood elves, drenei and naga sacrifice themselves to give a distraction to Goodwood and Tyrande's troops to completely destroy Kil'Jaedens forces in the zone, leaving the demon lord alone. Kil'Jaeden manages to kill most of Goodwood and Tyrande's troops, but when he's about to take the life of the Priestess, Illidan appears and defies Kil'Jaeden to a duel. Kil'Jaeden accepts the duel with a laugh, but to his surprise, Illidan sacrifices himself in a suicidal magical attack that severely wounds the demon lord. Tyrande and Goodwood, with the help of a lightly recovered Malfurion, manage to bring down Kil'Jaeden, who barely escapes through a dimensional rift. Goodwood, Tyrande and Malfurion part to the Well of eternity, where they join forces with Jaina and Thrall in an epic battle against a horde of demons who spawn constantly from the vortex. Finally, the Azerothian forces manage to kill Lord Rhoggeir and open a way to the vortex. Medivh appears once again and confesses that the reason he survived his own assasination during the first war is the link he shares with Sargeras, that allowed the Dark Titan to control him and create the Dark Portal, but also allowed Medivh to hold back the power of the Burning Legion. After that, he jumps into the core of the vortex, sacrificing himself to completely destroy the eye of Sargeras in a chain reaction that would close the vortex and banish all the demons on Azeroth back to the Twisting Nether.
Meanwhile, in the top of Icecrown Citadel, Darius informs Lady Sylvannas that most of the forsaken forces have been destroyed by Illidan and that the demons compeltely destroyed Lordaeron. The Black Queen completely ignores Darius and kicks the pierced and frozen corpse of Arthas out of the border of the citadel. Then she opens Ner'Zhul's spellbook and sits on the frozen throne.