Sentinel is a paradigm role whose main function is to shield allies from enemy attacks with enhanced defense. They can counterattack after taking on enemy attacks. The role is symbolized with the initials SEN and the color yellow. Snow particularly excels in the role due to his highest HP and access to all the Sentinel abilities, while Sazh also majors to a lesser extent due to his high HP and having Wards and Steelguard. Fang learns all the abilities of Sentinel just as Snow but she has lower HP. Hope learns more skills than Lightning and only lacks one passive ability. Lightning has the potential to be a good Sentinel despite her low HP due to her learning of almost all the skills and all the passive ability. Vanille is a weak Sentinel and only learns Reprieve and Mediguard.
Cid Raines can use the defensive shift based on Sentinel that grants him access to guard.
Sentinel reduces incoming damage. Serah and Noel start with Sentinel, but only Noel specializes in the role despite both of them learning all the passive abilities, with Noel learning the abilities that depend on the length of his guard. The role loses Evade, Counter, and Elude, but gains Element Guard. There are also numerous Paradigm Pack monsters that serve as Sentinels. Lightning in the Lightning's Story: Requiem of the Goddess DLC scenario has a role based on the Sentinel called Knight that allows her to conserve any buffs done to her.
Although no longer having access to the role, Lightning can still use Sentinel's abilities. Fang can use Mediguard.
A sentinel is a person or thing that watches or stands as if watching.