azhrei_fje wrote:
I had a vampire villain create his resting place for his coffin inside a large "bubble" in volcanic rock about 3,000 feet in from the edge of a mountain.
The rock was porous enough that he could return to his coffin in gaseous form but just about no one would be able to follow him. And it was far enough that a Locate Object spell used later wouldn't be able to locate his general direction either. :)
So he could return to his coffin in gaseous form but afterwards how would he leave his coffin? From what it sounds like you've trapped your villain in their coffin for eternity with a way for him to return but no way out.