Draegloth Favored One � Kill the demon to progress deeper into the catacombs
Rhylfang � Kill the spider queen - Rhylfang - to gain access to the portal
High Priest of Ghaunadaur � Kill the cultist to receive the Sygil of Ghaunadaur that you need for the Cult of Ghandaur side quest
Steel-Toothe � Kill the bear to complete the Big Game Hunting side quest
Thoregg � Use Search to find the merchant. He can sell you spider eggs that will fight for you, when they hatch
Kerendor � Try to save Kerendor
Morlesh � Talk to Morlesh and give him back the symbol of Ghandaur to complete this quest
Cultists � Kill the cultists to remove the first seal from the door
Kill the cultists to remove the second seal from the door
Kill the cultists to remove the third seal from the door
Chests � Search the room and loot the chests here
Altar � Use the altar to open the portal to Underdark
Chest � Loot the chest
Secret door � Use Search to find the secret door to the treasure
Remains � At the corpse, there is another ruby that you need for the Marked Rubies side quest
Secret door � Use Search to find the secret door
Sarcophagus � Search the sarcophagus to find the first half of legendary boots
Dusty Tome � Use Search to find the dusty tome. Inside, you will find the second page that you need for the Alteration Observation quest
Altar of Ghaunadaur � After you use the altar, you can receive a powerful invincibility potion
Secret door � Use Search to find the secret door
Remains � Loot the ramains for the log of the builder. You are going to need it to open the secret door to Gilded Eye Chapterhouse