The Fathomless Mastery is the third full length album by Swedish death metal band Bloodbath. Former Scar Symmetry vocalist Christian Älvestam performed guest vocals on the sixth track, "Iesous". The outro of the final track, "Wretched Human Mirror", features samples from the movie I Am Legend. A video was made for "Hades Rising". The album appeared at No. 45 on the Heatseekers Chart. The album was reissued in 2011, containing the tracks from the Unblessing the Purity EP released in 2008.The Fathomless Mastery is the last studio album with Åkerfeldt in the band.