Part of a complex that catalyzes the reversible reduction of CoM-S-S-CoB to the thiol-coenzymes H-S-CoM (coenzyme M) and H-S-CoB (coenzyme B). Catalyzes the transfer of electrons from ferredoxin to CoM-S-S-CoB during methanogenesis from acetate. Electrons transfer from ferredoxin to CoM-S-S-CoB via HdrA2, HdrC2 and HdrB2. In addition, the complex can use electron bifurcation to direct electron pairs from reduced coenzyme F420 towards the reduction of both ferredoxin and CoB-CoM heterodisulfide. This activity may take place during Fe(III)-dependent anaerobic methane oxidation. coenzyme B + coenzyme M + 2 oxidized [2Fe-2S]-[ferredoxin] = coenzyme M-coenzyme B heterodisulfide + 2 H(+) + 2 reduced [2Fe-2S]-[ferredoxin] coenzyme B + coenzyme M + 4 H(+) + 2 oxidized coenzyme F420-(gamma-L-Glu)(n) + 2 reduced [2Fe-2S]-[ferredoxin] = coenzyme M-coenzyme B heterodisulfide + 2 oxidized [2Fe-2S]-[ferredoxin] + 2 reduced coenzyme F420-(gamma-L-Glu)(n) Binds 4 [4Fe-4S] cluster. Binds 1 [2Fe-2S] cluster. Cofactor metabolism; coenzyme M-coenzyme B heterodisulfide reduction; coenzyme B and coenzyme M from coenzyme M-coenzyme B heterodisulfide: step 1/1. The ferredoxin/F(420)H(2)-dependent CoB-CoM heterodisulfide reductase is composed of three subunits; HdrA2, HdrB2 and HdrC2. Induced by growth on methanol or acetate. Belongs to the HdrA family.