When a character or monster is paralyzed, asleep, held, or otherwise completely unable to move, he or she is said to be helpless. There are numerous ways to become or cause a target to become helpless, a few are: being held by hold person, incapacitated, or getting hit by the sleep spell. All attacks made against a helpless target will be Critical Strikes on any roll other than a Natural 1. Because of this, a helpless target is extremely vulnerable.