Skal`s Waking Nightmare - Drewind Cliffs  

I've had these spawn off of Roots of the Black Oak, a mountain griffon and a bonestitch golem. I'm thinking they may spawn off of anything in the zone, but I've had a much higher spawn rate on the griffons and golems than on the roots...somewhere around 1 in 20 there as opposed to 1 in 100 on the roots.