Efficiency

Level 4 of the Dungeon
(0, 0, D:4)
  a +0 robe
(5, -9, D:4)
  an amulet of magic regeneration

Level 5 of the Dungeon
(0, 0, D:5)
  17 stones
(23, -38, D:5)
  17 stones

Level 6 of the Dungeon
(0, 0, D:6)
  a +0 leather armour