Urn of King Terenas

The Urn of King Terenas was a magical urn which contained the ashes of King Terenas. After being claimed by the Scourge, it was instead used to store the remains of Kel'Thuzad.

History
As part of a plot to summon the demon lord Archimonde, the dreadlord Tichondrius ordered the death knight Arthas to revive the necromancer Kel'Thuzad. However, a being of Kel'Thuzad's power could only be reanimated using the energies of the Sunwell, and Kel'Thuzad's remains were too badly decomposed to survive a journey to Quel'Thalas. Tichondrius therefore charged Arthas with stealing an enchanted urn from the Knights of the Silver Hand, in which the remains could be stored and protected. After killing Uther the Lightbringer, Arthas dumped his father's ashes out of the urn, then had Kel'Thuzad's remains placed inside it.

After defeating the high elves, Arthas poured the necromancer's remains into the Sunwell, defiling it and allowing Kel'Thuzad to be reborn as an undead lich.

Source
This item appears after Arthas kills Uther in Digging up the Dead, the second chapter of the Warcraft III undead campaign Path of the Damned.

Notes and trivia

 * As a result of Arthas' actions, the tomb of Terenas in Lordaeron's palace lies empty.
 * The Urn of King Terenas shares an icon with The Phylactery of Kel'Thuzad. As a lich must bind its soul to an object during its transition into undeath, the urn likely became Kel'Thuzad's phylactery. In the non-canon Heroes of the Storm, Kel'Thuzad confirms that the urn that Arthas got from Uther became his phylactery.