Efficiency

Level 4 of the Dungeon
(8, -13, D:4)
  10 gold pieces
(10, -15, D:4)
  6 gold pieces
(14, -11, D:4)
  12 gold pieces

Level 5 of the Dungeon
(0, 0, D:5)
  2 throwing nets
(3, -4, D:5)
  19 stones
(4, -12, D:5)
  a scroll of identify

Level 6 of the Dungeon
(0, 0, D:6)
  a potion of attraction