Once per day, a samurai can challenge a foe to combat. As a swift action, the samurai chooses one target within sight to challenge. The samurai's melee attacks deal extra damage when made against the target of his challenge. This extra damage is equal to the samurai's level. The samurai can use this ability once per day at 1st level, plus one additional time per day for every three levels beyond 1st, to a maximum of seven times per day at 19th level.
Challenging a foe requires much of the samurai's concentration. The samurai takes a –2 penalty to his Armor Class, except against attacks made by the target of his challenge.
The challenge remains in effect until the target is dead or unconscious, or until the combat ends. Each samurai's challenge also includes another effect, which is listed in the section describing the samurai's order.