Done with atk power 8 (probably the minimum you will have at this point). If you haven't aggroed the Shichimen already (you probably have) then the shuriken and running away aren't necessary to get the stealth deathblow. I kill the electric dog at the beginning because it very occasionally will aggro during the fight. Also, make sure not to back up too far towards the dogs at the far end of the ravine or they will aggro also. I get basically this exact same behavior from the Shichimen every time if I wait a bit over a second before running after the initial deathblow.
29 май 2019
