Cup of Sorrows
The Cup of Sorrows is the key to the Underdark whose door is located in the temple room of King Kobold’s Lair. It is considered the easiest and fastest way to get into the main city of the underdark, and is used primarily as a means for commerce and travel into the Underdark.
It is activated when placed into the lock dais in the temple and filled with blood. When those tenets are met, the chalice opens the hidden door to the Underdark.