Efficiency

Level 4 of the Dungeon
(0, 0, D:4)
  a book of Displacement (still there?)
  4 gold pieces (still there?)

Level 5 of the Dungeon
(0, 0, D:5)
  5 gold pieces
(10, 23, D:5)
  5 gold pieces
(11, 14, D:5)
  10 stones

Level 6 of the Dungeon
(0, 0, D:6)
  a scroll of vulnerability