SGPrometheus already wrote a definitive guide to Carolyn, but with the Innsmouth conspiracy, she's playable in a fourth archetype, blendable with the other ones. Holy Roller.
It's entirely due to the Book of Psalms. A card that’s decent for others is a godsend* for Dr. Fern, paying for itself +1, healing potentially eight horror from your teammates with hypnotic therapy in play (more with knowledge is power).
Add Rite of Sanctification, and spiritual therapy is very possible. Your super expensive assets are now much cheaper, adding 10 bucks to the party with an action and a card. You can pair this with more support or clue hunting, because a better bag makes you more capable of anything. Get out your appointment book, there’s a new way to play Carolyn.
*Ha ha?