Cosmic evolution of the most distant and powerful jets

About 10% of accreting supermassive black holes at the center of galaxies are capable of launching extreme relativistic jets. When pointed close to our line of sight, these are called blazars. Shining as bright as a hundred trillion Suns and detected at the dawn of time, blazars are of great astrophysical importance as they can provide us crucial information about the origin and growth of supermassive black holes in the early universe, and its connection to jet triggering mechanisms. The all-sky Swift-BAT instrument has enabled us to find the farthest and most luminous of these objects at hard X-rays. Using the latest 105 months BAT catalog, we could derive the most up-to-date blazar X-ray luminosity function, and understand how this source class evolves through cosmic time. In this talk, I will present the most recent results on the evolution of the most powerful persistent objects in the universe, highlight prospects for MeV blazars science in view of a future all-sky MeV mission, and discuss predictions for neutrino detections.