I've done ALOT of research on finding the stupid Spirit Stone. These are the 3 locations I've tried:
Rotting cellar (Act 2 - Path to the Oasis)
Watch Tower (Act 1 - Nothern Highlands)
Sheltered Cottage (Act 1 - Fields of Misery)
I've spent over 5-6 hours trying these locations and still nothing...
The Vendor at the Rotting cellar only has Heath Potions
The Vendor at the Sheltered Cottage sells junk, no spirit stone
Watch Tower, after over 50 tries I still haven't see it appear.
If someone has found it, can you please tell me where you found it? Also, what Level were you playing on?