Why are blazars so full of energy?
Because of its accretion disk
A black hole get its accretion disk when it gets close to a star. The gas from the star gets in an orbit around the black hole, slowly traveling towards the middle.
When gas in an accration disc of a blazar gets closer the black hole, its temperature rises and making plasma that spews out of the black hole and shoting away a high-energy photon beam, making the most luminous object in our universe.