Specifically, a spokesperson for Warner Bros. TV says that Collins will appear as a guest star in Episode 17 as well as in “at least two additional episodes” beyond that — though not necessarily as fallen angel Castiel.
Update: 23:50 Misha Colins to Return for Three Episodes
From TV Guide
Misha Collins will be returning to #Supernatural! Story coming soon...
We'll post more as we get it.
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