Fel Moss

Background
The origins of the Fel Moss seem to start when Malfurion caused roots to sprout from the broken piece of a wooden shaft embedded in Xavius' shoulder. Malfurion's casting had done more than simply keep it embedded; roots also grew within the wound, the wood feeding from the satyr's very lifefluids. The roots were now so much interwined with his system that whatever they felt, so, too, did Xavius. His claws turned gnarled, becoming tiny branches with burgeoning leaves. The satyr's horns spread out, growing into thick, higher branches from which foliage then sprouted. Xavius was not so much becoming a tree-rather, his body was providing Malfurion's creation with the nutrients and building blocks to make itself. All trace of the satyr vanished as the tree that the druid had creation from the wooden shaft took full bloom. Eventually Malfurion tore the remains of Xavius from Teldrassil. The Bough of Corruption, the one last remnant of Xavius on Teldrassil, remained to torment the night elf people and is the source of the fel moss that has tainted the gnarlpine, the timberlings, and everything else.

Ursal the Mauler, chieftain of the gnarlpine tribe, used the evil powers of the Fel Moss to drive them mad.

Source
This item drops from:
 * Grell in Teldrassil
 * Grellkin in Teldrassil

As a quest objective
This item is an objective of The Woodland Protector.

Corrupting Influence
According to Raene Wolfrunner and Tarindrella, Fel Moss one of the agents responsible for the recent corruption of most Furbolg tribes.