With the coming of the undeadScourge, the Burning Legion as well as the humans and orcs, Tyrande Whisperwind and her night elf sentinels fight a desperate battle to save their beloved home of Kalimdor. She first reawakens her lover, Malfurion Stormrage, and then the Druids of the Talon, and finally the Druids of the Claw. She also decides to free the great betrayer, Illidan Stormrage, who is eventually instrumental in weakening the Burning Legion, but at a great cost. Finally, on the urgings of the Prophet - revealed to be Medivh the Last Guardian, she and Furion join forces with Jaina Proudmoore and Thrall to delay the Legion's advance upon the World Tree until a proper defense can be arranged. The Legion and the Scourge eventually overrun the defenders, and demonic leader Archimonde prepares to consume the energy of Nordrassil. But moments before he can strike, Furion Stormrage springs his trap. Unable to counter, Archimonde is destroyed in a colossal blast of energy that shatters the tree of life--but unlike Archimonde, the tree would heal and its roots would once again grow deep. Peace came again to Kalimdor, but only for a short while, as the great betrayer, Illidan Stormrage would seek revenge for his imprisonment.
If the game is completed in the hardest level, the player will see an Easter egg involving 3D models of StarCraft units fighting; they are then destroyed by an exploding sheep. Contrary to popular belief, this is not a preview of StarCraft II, a claim which Blizzard has vehemently denied.
Furion Stormrage's first name is changed to Malfurion Stormrage in the Frozen Throne missions.
A playable Hydralisk can be found as a secret unit in the Daughters of the Moon. When you get the ballistae, cut down the trees until you reach a small (really small) clearing. The Hydralisk has a lot of life and a piercing attack that does 120 damage. You can also see how the Hydralisk attacks by scrolling down to the model's point of view, which was ambiguous in the original StarCraft sprite.
For reasons unknown the Chimaera are not usable and thus makes this the only campaign in which players cannot use all their race units.