Quote Originally Posted by Morthis View Post
I understand that part, I'm just talking about spells that block teleport tend to be designed around blocking all extra-planar spells, which summons and callings are (at least I think summons fall under that as well).

I decided to look at epic spells to see how cloister might be made. Only seed I can see that fits is ward, and only way to keep the ward spellcraft DC realistic is by making it pick specific spells to block rather than blocking all spells (even then the DC would be unrealistic). So I guess it's possible cloister simply blocks teleport and greater teleport specifically, along with various divination spells. That doesn't explain why V's scrying wouldn't work (since it blocks specific spells in this case), but Rich has made it clear before that the story always comes before the rules.
There are a few good explanations out there that show how to make the DC of any epic spell easy.