Spell of Conjuration
The Spell of Conjuration is a dark spell that was cast by Ner'zhul in order to create new portals on Draenor and lead the Horde to new, unspoiled worlds to conquer. Three key artifacts were needed by Ner'zhul in order to create these portals: the Jeweled Scepter of Sargeras, the Book of Medivh, and the Eye of Dalaran.
During the process of the spell's conjuration, huge dimensional rifts crackling with the cosmic energies of the Twisting Nether appeared over the skies of Draenor. The energies emitted from these newly formed rifts tore apart the fabric of reality in Draenor and caused massive tidal waves, earthquakes, and volcanoes to erupt.
The effects of this spell were so powerful that it ultimately led to the catastrophic destruction of the Orcs' homeworld, the shattered remnants of which came to be known as Outland.