Second invasion The second invasion refers to the Burning Legion ' s second attempt to destroy the world of Azeroth through full - scale military action . Strictly speaking , the term refers to the latter half of the conflict usually called the Third War ( specifically , the part of the Third War from Archimonde ' s summoning at Dalaran to his fall at Mount Hyjal ) , though numerous other events , namely the outbreak of the undead plague , the arrival of the Lich King , and even the First War were lead - ins or preparations for the conflict . The invasion is divided in three parts : Synopsis . Archimonde was a lead character in this invasion and attempted to completely destroy Nordrassil . As he climbed the tree , the Horn of Cenarius was sounded , calling thousands of Wisp s — ancestral guardians of the forest — to self - destruct simultaneously while attacking Archimonde . The invasion failed with Archimonde ' s death on Mount Hyjal . It is analogous to the Third War . History . In the leadup to the second invasion , demon lords of the Burning Legion were summoned to Azeroth by those who would sow chaos , conflict , and destruction to further their own ascendance . One of the most powerful these forces attempted to summon was Archimonde , also known as " The Defiler " . Unfortunately , his great powers made his summoning difficult , but eventually through stealing an artifact of Medivh , the lich Kel ' Thuzad found a way . After his return to Azeroth , Archimonde gave leadership of the Scourge to his demon lord lieutenant , Tichondrius , who battled the remaining forces of elves and humans in northern Eastern Kingdoms around the kingdom of Lordaeron and the elven domain of Silvermoon . He personally destroyed Dalaran and then moved his fight to Kalimdor with the ultimate goal of destroying the elven World Tree , Nordrassil . He spent some time helping manipulate the orc forces corrupted by the blood of Mannoroth around Ashenvale forest , but suffered some setbacks such as losing Mannoroth and Tichondrius while heading to Mount Hyjal , location of Nordrassil . The loss of Mannoroth allowed a large portion of the orcs to turn against the Legion . Archimonde then proceeded with the original objective of the invasion . The mighty demonlord carried out the invasion to attack the World Tree , Nordrassil . By draining the Tree ' s energies , not only would Archimonde gain untold power , his demonic Legion will also be able to drain the night elves of their source of power and immortality . But Tyrande and Malfurion had allied with Thrall and Jaina Proudmoore , as well as the Shadowtooth dark trolls and the Barkskin furbolgs . Archimonde ' s ascent up Mount Hyjal was agonizingly slow , being forced to destroy every successive base with the help of Azgalor ( Mannoroth ' s successor as leader of the pit lords ) , the lich Rage Winterchill , and Anetheron . The bases , consisting of the humans , orcs and night elves , did slow his ascent - however , his cunning mind and monumental power enabled the Legion to defeat the bases very quickly , going up against Jaina Proudmoore and Thrall , until he reached the night elves ' base which he destroyed easily with a wave of his hand . He grew in size as he climbed , determined to destroy the World Tree . He calculated no one in the world at the time had the power to stop him . Yet he miscalculated . It was not someone who could destroy him , but rather many . Archimonde did not think that the gathering wisps were of threat to him or the Legion . As Archimonde climbed , Malfurion raised the Horn of Cenarius and called to the ancestral guardians . They rose from the forest and amassed around Archimonde . They fell upon him , detonating in a massive explosion that destroyed the demon warlock and incinerated the forests around the World Tree ; nature herself would not allow his defilement to occur .