Original Link (now dead) -http://www.zone.com/asheronscall/ASHEportalskulls.asp
The Sentinel Skulls
Across Dereth dungeon portals are variously marked by shrines, pedestals, arches, and dolmens. What these monuments signify and who erected them are not clear. These particular skull-topped pedestals bracket the dungeon portal outside the town of Glenden Wood. Local superstition has it that the skulls transmit the view of the surface world to magical mirrors and seeing-stones within the dungeon, but this seems unlikely. First, none of these legendary receivers seems ever to have been recovered; further, no magical apparatus resides in the skulls as far as any sorcerer can ascertain. The idea about the skulls persists, however, because some mysterious power takes care of them.
Several times the skulls have been vandalized, and each time the vandals, no matter how powerful, disappeared soon after, on a dark, overcast night. What's more, the pedestals were found fully restored the next morning by powers unknown. A new rumor has it that the stone skulls are real skulls covered with mortar -- and were taken from the vandals themselves to replace the ones they'd destroyed. However, since this idea first became widespread, no one has done them the harm needed to find out.