Encountered on quest:The Forgotten Tower
Drops quest item:Key of Terror
Can be used for Runewords
Her drops are split into two types: her special rune drop and her normal drop. Her special rune drop only goes up to Ist. Her normal drop goes up to Lo, but she’s no more likely to drop a Lo rune than any other monster. In fact, she’s quite a bit less likely to drop a Lo rune than random ghost monsters on the same floor as her, since her normal drop tables don’t favour runes that heavily.
Basically, if you really want to find your own Ist rune, countess might be a good place to farm it (although it’s still quite rare). If you want to find your own Lo rune, do Secret Cow Level, Chaos Sanctuary, Arcane Sanctuary or anything else.