Sorry...not much of an explanation. This pic was taken in the Arid Sea, Tyria. As the guardian states, it takes you to Crystal Overlook, Elona. I first found the one in Crystal Overlook with my Dervish, and tried to use it then, but was denied access. So I just went into Tyria and spent the day finding it...and there it is!
NOTE: Tyrian characters cannot span across if they do not have Nightfall, and the character from any of the campaigns must find BOTH portals before usage.
yes. atm, i don't think it should be a big deal - i thought it was at first, but yes, it takes you from prophecies to nightfall (and back), once you meet the above criteria...
i thought about it, and it does seem like a pointless "short-cut". no missions mention it, and the fastest way would still be traveling by town-hopping, or by boat.
maybe they could make a town there or something? a few more quests to add would be ok.