Efficiency

Level 6 of the Dungeon
(2, 13, D:6)
  14 stones
(7, 21, D:6)
  12 gold pieces
(8, 10, D:6)
  a scroll of enchant armour
(9, 6, D:6)
  a ring of willpower
(10, 21, D:6)
  11 poisoned darts