• Urn of King Terenas
• Formerly the container of King Terenas' ashes, this magically enchanted urn was chosen by Tichondrius to preserve Kel'Thuzad's remains.

Formerly the container of King Terenas' ashes, this magically enchanted urn was chosen by Tichondrius to preserve Kel'Thuzad's remains.

Source

Arthas can find this in Digging up the Dead, chapter 2 of the Warcraft III undead campaign, Path of the Damned.