While watching this episode, it's hard not to think of the movie The Witches of Eastwick.
The girls are left alone (Derek de Lint does appear at the very end of the episode) and receive guest Nicholas Oldman (John Pyper-Ferguson) who will help them figure out what an artifact that causes realistic visions is. (We of course know that Nicholas is an evil supernatural entity from the very beginning, as we see him kill a bum before the main characters even appear.)
Later, Nicholas comes back and seduces Kristin, and inspires her to become an artist. The next day, Alex gets suspicious, visits him and he inspires her to get in touch with her senses (by stuffing herself and obviously she never thinks that she'll get fat). Rachel, however, proves to be a bit of a challenge, giving him some work to do in order to acquire the artifact.
It's not a bad episode, but isn't one of the greats and lacks in the originality department.