The bloodrager's source of internal power grants him the ability to bloodrage. At 1st level, a bloodrager can bloodrage for a number of rounds per day equal to 4 + his Constitution modifier. At each level after 1st, he can bloodrage for 2 additional rounds per day. Temporary increases to Constitution (such as those gained from bloodraging or spells like bear's endurance) don't increase the total number of rounds that a bloodrager can bloodrage per day. The total number of rounds of bloodrage per day is renewed after resting for 8 hours, although these hours don't need to be consecutive.
A bloodrager can enter a bloodrage as a free action. While in a bloodrage, a bloodrager gains a +4 morale bonus to his Strength and Constitution, as well as a +2 morale bonus on Will saves. In addition, he takes a –2 penalty to Armor Class. The increase to Constitution grants the bloodrager 2 hit points per Hit Die, but these disappear when the bloodrage ends and are not lost first like temporary hit points. While bloodraging, a bloodrager cannot use any Charisma-, Dexterity-, or Intelligence-based skills (except Acrobatics, Fly, Intimidate, and Ride) or any ability that requires patience or concentration.
A bloodrager can end his bloodrage as a free action. When the bloodrage ends, he's fatigued for a number of rounds equal to twice the number of rounds spent in the bloodrage. A bloodrager cannot enter a new bloodrage while fatigued or exhausted, but can otherwise enter a bloodrage multiple times during a single encounter or combat. If a bloodrager falls unconscious, his bloodrage immediately ends, placing him in peril of death.
Bloodrage counts as the barbarian's rage class feature for the purpose of feat prerequisites, feat abilities, magic item abilities, and spell effects.