Arafel: A Hebrew word, meaning 'cloud darkness'; generally used in reference to the Apocalypse. Possibly derived from Exodus 13:21

• The Lord preceded them... by means of a cloumn of cloud to show them the way, and at night by means of a column of fire to give them light.

This word is used heavily in Frank Herbert's Dune universe in reference to the eventual complete extermination of humanity at the hands of evolving, hunter-seeker machines built by the Ixians for war; it is probable that these machines track their targets through prescience, which would explain the importance of Siona but this is not clear. Leto II's Golden Path is an attempt to avoid that fate by scattering humanity so far throughout the cosmos, and by making the escapees so hard to track that by sheer luck some seed of humanity would survive any onslaught.

'Arafel' is also a land in Robert Jordan's Wheel of Time series.