Hallucinations cause a character to view places and things that are
elsewhere.  
Although the surroundings the character sees may seem very real, they are
just
visions and dreams. Sometimes, however, these hallucinations can be
prophetic 
and allow characters to see into places they would never normally venture. 
Beyond the disconcerting effect hallucinations have on people, they are 
generally harmless unless combined with a situation wherein it is
imperative
the character clearly see the dangers before themselves. Spells that
protect
from illusions improve one's ability to see through hallucinations.