Earliest Entry to Fiend of Possession?

[Wombles]

As I recall, it depends on which savage progression you're using; one version requires you to finish it entirely first, and another only requires that you finish it... eventually. Could be after you hit level 30 for all the rule cares. Also as I recall, the more broadly worded, unbalanced one was the earlier one, unsurprisingly enough.

Interesting, any idea where to find that rule?

Edit: Found it Looks like its for templates only though.