“The Devil has painted your hair — but still, I recognize you!”
Professor Stokes declared war on the Collins witch two weeks ago, and to be honest with you, it’s not really going that well. He was trying to interrupt the Dream Curse, but Cassandra managed to get it jumpstarted again, and the curse is now a step closer to its final intended victim.
Stokes did score a point when he raised the spirit of Reverend Trask, the 18th century witch hunter who never actually managed to catch a witch. The revenant Reverend tried his best — setting Cassandra ablaze with ghostly fire — but she managed to put the flames out, and move on with her day.
But it’s not a fair fight, really. This war is being waged by “magic”, so the writers do whatever they want. Cassandra can say, “My powers are greater than yours!” but that just means that she has more plot points coming up.
The Dark Shadows audience is clearly okay with having villains stick around for an extended run, so the only way Cassandra can be destroyed is if her schemes become predictable and repetitive, or she gets sidetracked on a pointless B-plot. Fortunately for her, that will never ever happen.