3C 454.3 is the most variable and intense extragalactic gamma-ray blazar detected by AGILE and Fermi during the last 4 years . This remarkable source shows extreme flux variability ( about a factor of 20 ) on a time-scale of 24–48 hours , as well as repeated flares on a time-scale of more than a year . The dynamic range , from the quiescence up to the most intense gamma-ray super-flare , is of about two orders of magnitude . We present the gamma-ray properties of 3C 454.3 , comparing both the characteristics of flares at different levels and their multi-wavelength behavior . Moreover , an interpretation of both the long- and short-term properties of 3C 454.3 is reviewed , with particular emphasis on the two gamma-ray super-flares observed in 2009 and 2010 , when 3C 454.3 became the brightest source of the whole gamma-ray sky .