In this paper, we develop a high-energy three-channel parallel waveform synthesizer using a CEP-stabilized high energy Ti:sapphire laser [1] operating at 10 Hz, and demonstrate high-flux continuum harmonics from Ar gas target. Our three-channel waveform synthesizer consists of a Ti:sapphire laser pulse (44 mJ, 28 fs) and an infrared OPA (signal: 6 mJ, 33 fs, idler: 3 mJ, 40 fs). By combining the waveform synthesizer and the energy scaling method of HHG, a 0.1-μJ super-continuum supporting < 300 as isolated attosecond pulses at 48 eV is generated in the soft-x-region. To our knowledge, our obtained photon flux of the super-continuum in the soft-x-region is the highest value ever reported.