MostlyHarmless42
Adventurer
It's a fun premise, and there is no actual rule on it as written. Similarly, the "forbiddance" is likewise completely up to DM ruling as a weakness. After all, who according to rules can "invite" a Vampire in and what constitutes a residence vs a public building?
For myself, I take reference to what is traditional folklore regarding vampires. "Running water" in this sense refers to a body of water that is not at rest, i.e. a river or ocean. It references classic works like Dracula in which vampires cannot cross such bodies of water without aid. The point of this weakness isn't to kill a vampire, but keep it at bay.
I would rule therefore that casting move water on conjured water would not work. However, I would all controlling still water from a preexisting lake to qualify.
For myself, I take reference to what is traditional folklore regarding vampires. "Running water" in this sense refers to a body of water that is not at rest, i.e. a river or ocean. It references classic works like Dracula in which vampires cannot cross such bodies of water without aid. The point of this weakness isn't to kill a vampire, but keep it at bay.
I would rule therefore that casting move water on conjured water would not work. However, I would all controlling still water from a preexisting lake to qualify.