I was squeezing "Xanon Pass" through the Questimator.
What a fail!
2.5 BP from traps you cannot find because there is a Monster in the room with them.
5 BP from traps you can find (though searching each room for traps if you're alone takes a long time!)
and then easy little 21 BP from Monsters.
So the barbarian goes in with 8 BP and comes out with, like, minus 13 to minus 20 BP, depending if he finds the traps or not. That's not unbalanced, that's plain stupid! (plus the famous Yeti bug, of course)
A complete group with beginner stats would lose 10 BP, that's on the "very easy" side of normal.
I continued and simulated the monster damage with mercenaries:
one helbardier: 14.8 BP for Barbara, 16.8 for the group (death 93% from monsters alone)
two helbardiers: 6.7 BP for Barbara, 10.7 for the group (death 35% from monsters, but traps come on top!!!)
three helbardiers: 2.6 BP for Barbara, 6.7 for the group. (death 2% from monsters... traps are balanced here)
With three mercenaries he has a chance to survive the monsters plus the traps.
For me that makes three possibilities:
1. They didn't know, test and care. I don't believe that.
2. The developer made a group quest and later in the process, after a group play test, they changed the text. This is because as a group quest, Xanon Pass is really easy. It would also explain the Yeti bug.
3. It was supposed to be played with 2 or 3 mercenaries, but they forgot to mention it in the quest book.
So my recommendation is, add to the quest book introductory text this line:
This quest is best played with a beginner Barbarian
and three halberdiers.