For Absent Friends and the trolling around the Fate Chain spawn.

[Jeeqbit]

Sorry but I don't believe it. Sartauvoir isn't even in that skirmish whey would that Skirmish which has Dyunbu as the main opponent drop a Sartauvoir note.

Obviously it's very rare but again I was on an alt so I could play with a friend and unexpectedly it dropped from there, and they appear in the skirmish that follows.
Maybe it was the one that followed but I doubt it because the one listed on websites is Help Wanted.