Long ago, before Human civilization had progressed into kingdoms and civilized society, the Kaldorei of Kalimdor participated in a war that ultimately split the world apart. The war was about power, as all wars ultimately are in Azeroth -- this time, the powers of a mysterious font of energy known as the Well of Eternity. Suffused with arcane magics, the Well commanded the attentions of countless Highborne who grew dependent on its powers. So too, did the Well draw the attention of the dark forces of the Burning Legion and its leader, Sargeras.
Though the War of the Ancients ended in a victory for the Night Elves, it wasn't the last they'd see of the Well of Eternity. In an act of desperation to keep the arcane font alive one way or another, Illidan Stormrage used a vial of water from the original Well to create a new one, high atop the peaks of Hyjal. Horrified by his actions, his brother Malfurion had him imprisoned, and the Aspects created the World Tree and charged the Kaldorei with guarding the new Well. The practice of arcane magic was forbidden from use in Kaldorei society, punishable by death.
But the Kaldorei underestimated the depths of the Highborne's addiction. And both Highborne and Kaldorei alike didn't realize there were far worse, darker powers to worry about ...
Today's Know Your Lore is a Tinfoil Hat edition, meaning the following is a look into what has gone before with pure speculation on why it happened. The events presented are events that happened in Azeroth's history, but the conclusions are merely theories and shouldn't be taken as fact.