On the wiki, the shaman quests stop at #5. There was "evidence" linked here:
https://www.project1999.com/forums/s...1&postcount=12
However, with Green/Teal causing the wiki to have all the patch notes, I found this from here:
https://wiki.project1999.com/Patch_Notes
June 27, 2001 3:00 am
(NOTE: This patch was not in Allakahazam and came from
http://web.archive.org/web/200109260...ww.neriak.com/)
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Quest Changes **
The Iksar Shaman 6th Skull/cudgel quest should be working now.
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So it looks like the 6th skull quest IS supposed to be in-game.