Type insanity; Save Will DC 20 Onset immediate Effect –4 penalty on Will saving throws and all skill checks; loss of memory (see below)
A character suffering from amnesia cannot remember things; his name, his skills, and his past are all equal mysteries. He can build new memories, but any memories that existed before he became an amnesiac are suppressed.
Worse, the amnesiac loses all class abilities, feats, and skill ranks for as long as his amnesia lasts. He retains his base attack bonus, base saving throw bonuses, combat maneuver bonus, combat maneuver defense, total experience points, and hit dice (and hit points), but everything else is gone until the amnesia is cured. If a character gains a class level while suffering from amnesia, he may use any abilities gained by that class level normally. If the class level he gained was of a class he already possess levels in, he gains the abilities of a 1st-level character of that class, even though he is technically of a higher level in that class. If his amnesia is later cured, he regains all the full abilities of this class, including those gained from any levels taken while he was suffering from amnesia.
Pathfinder RPG GameMastery Guide, © 2010, Paizo Publishing, LLC; Authors: Cam Banks, Wolfgang Baur, Jason Bulmahn, Jim Butler, Eric Cagle, Graeme Davis, Adam Daigle, Joshua J. Frost, James Jacobs, Kenneth Hite, Steven Kenson, Robin Laws, Tito Leati, Rob McCreary, Hal Maclean, Colin McComb, Jason Nelson, David Noonan, Richard Pett, Rich Redman, Sean K Reynolds, F. Wesley Schneider, Amber Scott, Doug Seacat, Mike Selinker, Lisa Stevens, James L. Sutter, Russ Taylor, Penny Williams, Skip Williams, Teeuwynn Woodruff.