Head to the Wanderlust Fair in Darklight Wood and talk to everyone, especially Torbus Finlow. He tells you to go to the shadow oak. The actual quest starter is the mutilated deer at 191.37,-43.61,167.14
3 pieces of clay (From clay golems: there are some on way to lab but other golems in zone will also update)
5 blacksmithing materials (in the room with the blacksmith also near the lab, clicky updates look like pots of smelted metal on ground)
5 alchemical materials (in the lab, you need to get into secret room, head into library area under stairs, go to table furthest back click candle on table to open bookcase secret wall look around in there for bottles that are clicky updates. candle on top of bookcase next to door reopens wall).
Return to Gimble Tinkerton
Go to Chelsith and gather goo from the leviathan's excretions.
You can not be grouped with anyone but a Fury who is on the same step in order to zone in, or even see that the rock is clickable to zone in.
Level 90 Mythical Conversion
Your Mythical Weapon has unique effects which will not work on level 81-90 spells, combat arts, or pets. By completing two quests, you may convert your Fabled or Mythical Epic Weapon into an Enervated Weapon and add persistent Mythical Effect spells to your knowledge book. This allows you to acquire other weapons without losing class-defining Mythical effects.
The quest requires that your class and your Epic weapon match. You will only receive the mythical spell gem of your current class.
You can start this series as long as you have the fabled version of your epic. But if you have completed "Epic Repercussions" then you will not be rewarded the mythical weapon if you go back and complete your class specific Kunark mythical quest.
The quests which make your Epic Weapon effect into a spell is the same for all classes.