Kill the Aqua Goblin Oracle (level 30^^^) ( 785, 51, 222 ) /waypoint 784.66, 50.87, 221.86 to get the brooch to start quest. Only 1 character may loot the brooch, and the HQ is not shareable, so you will have to kill the Oracle multiple times to start the quest for everyone in your group (respawn is 10 minutes).
One of the chess tiles ( -788, 101, -16 ) /waypoint -788, 101, -16 has a harvestable loose stone. Collecting it will trigger a trap, spawning four linked 34^ triggered guardians. If you looted the key from Zannas of the Arm (previous step), it will deactivate the trap and they won't spawn. You will always receive Tessa's Hidden Notes for Zannas regardless of if you kill the triggered guardians or not.
There are three mine openings, enter the rightmost mine at ( -1470, 118, 199 ) /waypoint -1470, 118, 199.
Speak to a punished magi apprentice ( -1620, 48, -30 ) /waypoint -1620, 48, -30. You must be able to speak Orcish to communicate with to him. He wants the cleric helms from four clerics of Hate to prove you are not a Crushbone spy.
Enter Crushbone Keep. Slay four clerics of Hate on the second floor in the Hall of the Magi ( 70, 25, -36 ) /waypoint 70, 25, -36 to obtain the cleric helms. Most of the other mobs in the room are place holders for the clerics of Hate. Clerics can also be found in the Emperor's Chambers ( -13, 22, 31 ) /waypoint -13, 22, 31 and at the Royal Guardpost ( -60, 25, -28 ) /waypoint -60, 25, -28. The oracles of Hate do not work. You may have to clear the room a couple times to get all four to spawn.
Slay every watchful sentry you encounter: they carry keys that unlock doors to allow further progress.
The first sentry at is at ( 59, -6, -15 ) /waypoint 58.57, -6.43, -15.18. He dropped a key that unlocked the first door, which is at ( -43, -10, -67 ) /waypoint -42.60, -9.81, -67.35.
Once you go through this door, there is a sentry in the corner at ( -68, -10, -61 ) /waypoint -67.91, -9.83, -61.10. He dropped the key to get through the second door at ( -65, -10, -82 ) /waypoint -64.71, -9.83, -81.94.
Go through the secret door at ( -65, -10, -165 ) /waypoint -65, -10, -165.