Ultima Underworld Walkthrough - The Tripartite Key
You need the Tripartite Key to get access to the chamber where the Slasher of Veils is tied by magical means. The Tripartite Key consists of three single keys which you must acquire to build this key.
The Key of Love
Talk to Bolinard (L7) and get the picture of Tom. Visit Judy (L5) and hand over the picture to her. Judy will be overwhelmed by the refreshed memories of her beloved lover. A single tear of Judy will drop into the lava and create the Key of Love.
The Key of Truth
Free Illomo's friend Gurstang (L7). He will tell you about the Key of Truth and ask you to visit Illomo. He will also confide the password Folanae to you. Ascend to Level 6 and talk to Illomo. After telling him the password he will conclude that a book in the library bearing the word Folanae could contain further information how to get the Key of Truth. He will also tell you that one must cast a special mantra at a shrine to reveal the key. There is only one appropriate book (L6:I3..13) titled Folanae Fanlo in the Academy's library. Chant the mantra Fanlo at a shrine and the Key of Truth will appear.
The Key of Courage
Visit the mountainman Smonden (L7). He will tell you about the Key of Courage and hand over a key (WK) which will give you access to a staircase in the northwest of Level 7. Follow this staircase and fight your way up to level 3. There are two towers connected by a wooden bridge. Smash the door of the tower in the west and get the key from the gold coffer. Unlock the door of the eastern tower with this key and take the Key of Courage.