The item, Flute of Xavaric starts this quest. It drops off of Xavaric in Felwood. You can obtain the Jadefire Felbinds by killing the various Jadefire Satyrs, Jadefire Betrayers, Jadefire Tricksters, etc.
Bring the Flute of Xavaric and 5 Jadefire Felbind samples to Eridan Bluewind in southern Felwood.
The flute drops off of Xavaric, who is in Northern Felwood. You can obtain the Jadefire Felbinds by killing the various Jadefire Satyrs, Jadefire Betrayers, Jadefire Tricksters, etc. Once you collect enough of the Felbinds, head to Eridan Bluewind, who is in the south of Felwood, with some other Cenarion Circle members.
You study the simple wooden flute you picked up after defeating Xavaric.
The knotted wood feels solid, but it seems as if the spirals and patterns in the surface begin to spin and move as you turn it over in your hands. Suddenly, you feel a sense of dread...
You shake your head, sure that your mind is playing tricks on you.
It's possible that other satyrs carry clues as to what you have found. Bring your findings to the druid, Eridan Bluewind, that lives in southern Felwood.
What is it, <class>? You look concerned.
I sense the suffering of ancient ones, <name>...
Holding these items is almost unbearable...