"You haven't been a Basilisk or else you wouldn't need me to tell you about it." Sirius stared up at the bat. "If you want to leave us and save your own skin then fine. You can fly back up the pipes." Sirius pointed back to the way they'd came as he spoke.

He turned to Roger. "The scales repel magic. I don't know if even the Sword of Gryffindor can penetrate its scales. I don't know how resistant they are to your weapons either." He paused for a moment to think but he kept glancing around, looking for any movement from the shadows. "There aren't any scales in its mouth so that's its weakpoint. The trick is hitting it there without being bitten. The venom should kill you in minutes." Less than that, if he remembered right.