User blog comment:MrAnonymous/What should the final episode ever be about?/@comment-5237627-20121229063226

They should introduce a davea, a human possessed by an angel and the blood of a demon (epicness), should be younger than Castiel. The davea must be introduced in mid S9 - S10 mid.

Vulnerabilities:

Dean and Sam die trying to kill it (half demon blade and angel blade, half holy water with whatever kind of liquid the angels are highly allergic to).