Kelani Magi

The Kelani Magi were the creators of the Enchanted Gemstones, said to hold the power to make constructs out of pure energy. When the Kelani fell to ruin, the Razormane quilboars were quick to scavenge and covet these beautiful and powerful objects. One such stone was retrieved by Cairne Bloodhoof in the Horde's search for the Oracle said to reside deep within the caverns within Stonetalon Peak, and used its powers to power an enchanted bridge deep within the ruins beneath the mountain.

Trivia

 * The orb and its lore were made by Warcraft III level designer David Fried who was responsible for making item tooltips.
 * "Kelani" could be a reference to StarCraft's Kelanis Guild, one of two factions that created the Kel-Morian Combine, which were mentioned in the first StarCraft's manual.

Speculation
Next to nothing is known for certain about the Kelani, other than arcanistry and their strong links to the ruins beneath Stonetalon Peak. Trapped within the same caverns that required Cairne's gemstone to access was Aszune, a former night elf princess. As such the Kelani Magi were likely an order of Highborne night elves at some period in history, and the enchanted, peril-filled ruins beneath Stonetalon were of their construction. The powerful undead that haunted the area were thus likely the cursed remains of these Magi. This is a fate shared by many groups of Highborne across Kalimdor (such as the majority of the Shen'dralar). They may have some relation to the undead servitors of Lord Talendar, deep within the Tomb of the Ancients under Dustwallow Marsh.