Labyrinth of Kindo'jan
The Labyrinth of Kindo'jan was released in Patch 12.1.5 with the limited-time Fabled Let Me Solo Him: Kindo'jan achievement. Similar to previous Nemesis bosses, this achievement is awarded to anyone who defeats Kindo'jan during the initial week of the Patch, but has since been extended an additional week due to many, many bugs in Labyrinths.
Unlike previous, traditional Nemeses, you can't just walk in and fight Kindo'jan. He becomes available after all 9 chambers of the Labyrinth are completed, which usually takes at least 45 to 60 minutes, and there are no save points in the run. On the upside, as players need to unlock all 9 chambers, they are actually able to acquire an insane amount of stats from Mislaid Curiosities, collect Hexmasks for bonus damage, and pick up Conduits before fighting the boss, which likely makes this boss much easier than intended. Many players have claimed to kill the boss in less than 90 seconds - before the Intermission!
With all these changes to the typical Nemesis boss formula, over 150,000 players have now defeated Tier 11 Kindo'jan during the first week of Patch 12.1.5 across both NA and EU servers. NA has over 70k kills, while EU has over 82k kills, and there's now another week to go.
We'll have to see how many players will claim the Fabled: Let Me Solo Him achievement and the title after the second week.
