Ninjas have four job specific skills. Each skill can be upgraded up to four times, by using stars earned from completing quests and instances. Upgrading your skills often will ensure that you're as powerful as you can possibly be.

click to enlarge
Ultimate Power: You gain energy for each critical hit you inflict.
Shrouded Armor: Your special armor reduces damage taken when struck.
Ninja's Grace: The way of the ninja grants improved run speed, faster health regeneration, and attack.
Dragon's Boon: The blessing of the dragon grants a chance to counterattack with a lightning strike that will damage a opponent and then chain to another opponent up to 3 times.