Natasha "Yggwilv" Zybilna is a wanderer of the multiverse, a visitor to Quelmar from worlds far beyond, potentially through a gateway such as Sigil or through another means of universe hopping.
About
Yggwilv's original universe is thought to be Greyhawk, though others believe she hails truly from Faerun, having only first appeared in the Greyhawk record.
In any case, it is likely that due to there being a Tsojcanth in Greyhawk and Quelmar alike, Tasha was drawn to the area of Isonhound to see what other echoes of her worlds lay across Quelmar.
She is known to travel via Yggwilv's Hut, a large shanty with chicken legs.