Shadowgate 64: Trials Of The Four Towers Codes -

Defeating Belezar:
Place the Dragon Eye on the false Staff of Ages.

Defeating the Warlock Lord:
Place the Staff Of Ages followed by the Ring Of The Kingdom in the hands of the Lord Jair statue.

Passing the fourth trial:
Collect all three rings from the Inner Chamber of Tower 2. Equip the blue ring during the maze in the fourth trial to reset the controls to normal. Go through the maze and remove the ring after you exit.

Finding the Rusty Key:
Look between the column and the wall in the room with the custodian's note to find the Rusty Key.