The Riddle of the Imps puzzle is solved by speaking with each legendary hero/heroine to gather clues helpful to determine which specific item they provide, and which item they require. It is simply a process of matching.
Action needed[]
Place the item each one requires in the associated chest located behind that specific figure. When all chests are filled correctly, the puzzle is solved, and this triggers dialogue from the Imps.
Solution[]
The correct item for each hero's chest is as follows:
Elminster: Pipe
Khelben: Quarterstaff
Alustriel: Pendant
Piergeiron: Helmet
Drizzt: Scimitar