I found the paragraph I was looking for on P17 of the book:
This is one of the three first level class features of the Druid:
"
Druidic Awe: Druids are sacred priests, raised above ordinary folk and touched by the gods. Slaying a druid is an
unimaginably evil crime, and even striking one is absolute anathema to commoners and nobles alike. To attack a druid, a character must first succeed at a Will save (DC 10 + ½ druid’s class level + druid’s charisma bonus). A success indicates that the character may attack the druid during this encounter; a failure means he may not. The Druidic Awe ability is immediately cancelled out if the druid performs any obviously offensive actions towards the target or his allies, including casting spells on them. "