A Vortex

Perhaps they forgot to add in a way for Orun to communicate with them so he could inform them of his coming beforehand and give them time to prepare to deal with situations like this.

Or the Elves did not forget and only just decided to not add it in. Orun couldn't tell which one it was.

He could try asking Oracle if there was a way to break through the barrier, but that doesn't sound user friendly in his ears, and he doubts that the Elves will think otherwise about it.

Orun is yet to discover what kind of people the Elves really are, so doing things too rashly could end up leading to several complications for him, and he doesn't want that.

"from where I see things, we have two choices on our hands. We can either go back home or stay long enough for anyone to come through the barrier and hopefully get us into it".