Plot of Movie
Draenor, the homeworld of the orcs, is dying. An orc warlock known as Gul’dan unites the orc clans and forms the Horde, and creates a portal to the world of Azeroth. The orcs begin to use fel magic to drain the life out of captive draenei in order to sustain the portal. Once it is operational, Gul’dan leads a small warband to capture prisoners on Azeroth and sacrifice them to bring the entire Horde army through. Despite their doubts, Durotan, the chieftain of the Frostwolf Clan, his pregnant mate Draka, and his friend Orgrim Doomhammer join this initial warband. While crossing through the portal, Draka goes into labor. When the orcs arrive on Azeroth, Gul’dan assists Draka with giving birth, but the baby is stillborn. Gul’dan then drains the life out of a nearby deer to revive and infuse fel magic into the baby.
The orcs raid several settlements throughout Azeroth. Anduin Lothar, the commander of the Alliance forces in the kingdom of Stormwind, looks over some of the men that were killed, and finds a trespassing mage named Khadgar, who explains that he was investigating the dead bodies because they contained traces of fel magic. Khadgar persuades Stormwind’s king, Llane Wrynn, to consult Medivh, the fabled Guardian of Tirisfal, and Llane sends Anduin and Khadgar to Medivh’s stronghold, Karazhan, to inform him of the fel magic’s presence on Azeroth. In the Karazhan library, a ghostly shadow leads Khadgar to a mysterious book, which he takes.
Anduin, Khadgar and Medivh join a scouting team following traces of fel magic, but are ambushed by orcs. Medivh uses a spell to kill most of the orcs, and the Horde’s warchief, Blackhand, flees, along with Durotan and Orgrim. Khadgar restrains the half-orc known as Garona, and the soldiers take her prisoner. King Llane frees Garona in exchange for loyalty to Stormwind, and she leads the humans to spy on the orc camp, where they learn of Gul’dan’s plan to bring the Horde to Azeroth. Meanwhile, Durotan realizes that the fel magic is responsible for the destruction of Draenor, and if Gul’dan is not thwarted, Azeroth will suffer the same fate. Despite Orgrim’s objections, Durotan invites Llane to a secret meeting so that the Frostwolf Clan and the humans can unite to defeat Gul’dan. While studying the book he took from Karazhan, Khadgar learns that Gul’dan could not have opened the portal on his own; he had help from someone on Azeroth. He is confronted by Medivh, who burns Khadgar’s research when Khadgar offers to help him. Khadgar later discusses the truth about the portal with Anduin, as well as Medivh’s actions against him.
The Frostwolf Clan meets with the humans to negotiate an alliance, but the group is ambushed by Blackhand. As the humans retreat, Medivh forms a magical barrier to protect them, but Lothar’s son Callan is separated from the rest of the group and killed by Blackhand. Medivh is severely weakened, and Garona and Khadgar take him back to Karazhan to recover. After noticing Medivh’s eyes shine green, showing that he is infected by fel magic, Khadgar returns to his former home, Dalaran, to seek help from a group of human magi called the Kirin Tor. Alodi, a legendary mage and the true identity of the shadow who led Khadgar to the book, reveals that Medivh has indeed been corrupted by fel magic and possessed by an unknown demon. At the orc camp, Blackhand purges the Frostwolf Clan. Orgrim helps Draka to escape and she sends her infant son, Go’el, down a river in a basket, but is then found and killed by another orc. Durotan challenges Gul’dan to Mak’gora, a traditional orcish duel to the death for leadership of a clan – in this case, all of the orcs. During the fight, Gul’dan violates the honorable combat rules by draining the life out of Durotan with his magic, killing him and earning the disapproval of the orcs watching, and he empowers Blackhand with the same magic. Medivh, now in a half-demonic state, starts to open the portal to Draenor, and Gul’dan sacrifices the captured human villagers to allow the rest of the Horde to enter Azeroth.
Llane leads the human army in an assault on the orc camp, while Anduin and Khadgar fight Medivh and destroy the demon that had begun to manifest on the outside. Medivh is left mortally wounded, and uses the last of his strength to close the portal to Draenor and instead open a portal to Stormwind, allowing Llane to evacuate most of the freed prisoners. When Medivh eventually dies, the portal closes, leaving Llane, Garona and a small number of human soldiers to fight the orcs. Llane secretly orders Garona to kill him, bringing her honor among the orcs and putting her in a position of power to bring peace to the two races. Garona reluctantly does so, and is welcomed into the Horde by Gul’dan. As the orcs celebrate, Anduin arrives to retrieve King Llane’s body and discovers Garona’s knife in the body, realizing that it was she who had killed their king. Blackhand challenges Anduin to Mak’gora, and Anduin quickly disposes of him. Against Gul’dan’s demands, the orcs, bound by tradition, allow Anduin to depart with Llane’s body. At Llane’s funeral in Stormwind, the leaders of the other human nations, along with the high elves and dwarves, proclaim an alliance against the orcs and rally behind Anduin as the commander of the Alliance. Elsewhere, Orgrim takes one of Durotan’s tusks to one day give to Go’el, and the basket containing Go’el is found by a human.