During prep for a Halloween celebration, original-series Trek villain Redjac materializes on the Enterprise and starts causing fear-based havoc, and the only way the crew can stop him is by turning their bodies and brains into classic movie monsters -- Troi as a mummy, Riker as a werewolf, Data as a frankenstein, Picard as Mr Hyde, and Worf as the "Klingon from the Qij Lagoon". I didn't know Trek comics could be this deliriously delightful, and now need to read more ASAP.
I wish this were an episode of the series. We got that Animorphs-y episode "Genesis", and the Robin Hood one -- why not this???