It is possible to save just before entering a level
in order to load and reload that next level to hunt for valuable
items. The best item to hunt for is a Wand Of Clone Monster.
Save a few Wands Of Clone Monster. When you get to the levels
with Hrungnir in Castle 1, or the Giant Kings in Castle 2, clone
off the Giants however many at a time you can without getting
killed in the process. When you kill off the cloned Giant Kings,
you will get enormous amounts of treasure.