Efficiency

Level 5 of the Dungeon
(1, 5, D:5)
  15 poisoned darts
(2, 5, D:5)
  a potion of curing
(12, 8, D:5)
  a +0 leather armour
(14, 10, D:5)
  11 gold pieces

Level 6 of the Dungeon
(4, 1, D:6)
  a scorpion corpse