Xaander

[quest=40423] is at 52.3, 58.6 in Highmountain. Take the east road from Thunder Totem to Snowblind Mesa then go north, follow the road and you'll come to the cave. Loot the treasure inside and a party of enemies will appear (Puck, Xaander, Zenobia, Darkful, Jak), kill them and loot the treasure.
He's a part of Adventurer of Highmountain achievement, has a chance to drop [item=138839], [item=140681], [item=140683], [item=140682].

For TomTom users:
/way Highmountain 52.3, 58.6 Unethical Adventurers

Unethical Adventurers location https://www.youtube.com/watch?v=OgTrTaNDfZs

Xaander — [item=140681] / [item=140683] / [item=140682] / [item=140680] / [item=131767] — https://youtu.be/5-rqkjLLPeA
TomTom: /way Highmountain 52.3, 58.6

For the achievement Adventurer of Highmountain you also need [quest=40423].
Coordinates: 52.4, 58.4 - Highmountain, Thunder Totem, Snowblind Mesa,
Flight point: Thunder Totem - [npc=95688]

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• start in "Thunder Totem" from the upper level and take the exit to the East to the "Snowblind Mesa". Goes over the two bridges and turn to the left. Follow the riverside until you reach a cave. Inside the cave click on [object=240353] and a group with 5 enemies will appear. There are the [quest=40423] consisting of Puck, Jak, Xaander, Zenobia and Darkful. Defeat them and don't forget to loot.
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I show you the way to [quest=40423] in this Video: https://youtu.be/91HHWLKHHy0