Sometimes it says that a level is terrorized that doesn't exist. You should then drop gold at the entrance to the city. This way, when you open the cow portal, the portal outside opens. Then a mixture of all enemies from terrorized areas appears together in one area. If the portal opens outside of the city, it says "no level" or something like that.
would be an option
UT levels can open outside of Town. and you can enter and come out of it ( itested it )
imo there should be a cow level full of andariel/duriel/mephisto/diablo/baal instead of cows
make it cost 12 standard of heroes to make the portal