The Portal to Teth was a special spell that Bael'zharon cast on random unlucky players during the Child of Daralet event back in December y2k. Anyone caught on the business end of this spell was not only portalled to Fort Tethana, but ABOVE it, at a Z-axis of approximately 5,280 feet above the surface.
All but the most robust players would not have survived the fall.
See also Portal (Spell).