Sunwell

Surrounded by the Sunwell Grove, the Sunwell was a fount of mystical power at a convergence of powerful ley energies in Quel'Thalas, created by the high elves who used a vial of sacred water stolen from the Well of Eternity. The well's potent arcane magic fed and strengthened all high elves on Azeroth. Thus, the Quel'Dorei capital of Silvermoon City was established. The power of the high elves grew, and they cast an enchantment on the Eversong Woods that would keep them bathed in eternal springtime. Elven magi crafted monolithic runestones along the borders of Quel'Thalas; these massive stones powered a magical shield intended to mask the elves' magic from extra-dimensional threats and protect the land from invasion. The hard-won peace of Quel'Thalas would endure for roughly four thousand years.
During the Third War, the Scourge came to Quel'Thalas with the intention of reawakening the Lich King's most faithful servant, Kel'Thuzad. They did this by submerging his remains in the Sunwell, tainting its waters and fouling its power.