Elves are just cleaning up in there, with the help of Blood to Soul. Most monsters are slow. Nightmare doesn't attack SOSC. Bone Dragon and Lesser Demon are the only difficult monsters. Lesser Demon doesn't appear to have a significant attack in close range and their ranged attack has a 4 cell range, so elves stay 5 cells away (they're slow to move too) and they just fire away. Since these are high level monsters, you can just sit there and gain experience and using Blood to Soul, you pretty much never have to leave.

9F Drops: Magic Gem, Blank Scroll (Level 4), Blank Scroll (Level 5), Dice Dagger, Old Belt of Soul, Old Belt of Mind, Katana, Plate Mail, Blessed Plate Mail, Chain Mail of Magic Resistnce, Scale Mail, Two Handed Sword, Blessed Two Handed Sword, Haste, Greater Haste, Pine, Brave, Res, Blue, Wis, Tame Monster, Strength, misc level 4-6 magic books, Ring of Immunity to Magic, Scroll of Enchant Armor (blessed and neutral), Scroll of Enchant Weapon (blessed and neutral), Demon Set.

Bone Dragon usually drops potions and gems, including Highest Quality Diamond. They also drop enchant scrolls (blessed and neutral).