Secret combination

The Secret combination is the second half of the way into the Abandoned Tower. You get it under your house, after you clear the blockage in the passage there (3 Bronze Details and 3 Wooden Planks). With the Inquisitor’s medallion from the start of the game, it opens the tower’s locked gate.

Opening the gate uses the combination up; the medallion comes back to you. It is a quest item, so it cannot be sold.