This level has a red runekey in it but no inactive glyph.
There is no indication anywhere that killing the Boss (Sorcerer) does
not
open the red runelocked door
SoB pg 19/20
Unless otherwise stated, the leader on each dungeon level carries a red runekey. Unless otherwise specified, upon the leader’s death (whether caused by the heroes or not), the heroes immediately receive it and can open the corresponding red rune-locked door.
).
It seems likely that the red runekey is a misprint for a red glyph. Rumour 11 in RtL had a red glyph misprint for Master Sorcerer and Level 6 had a glyph misprinted as active when it should be inactive, so similar misprints have happened.
So, thoughts?