At present, Fiend Sovereign Jadeface and Palatial Lord Black Dragon were inside the Grotto-heaven. They had no way of communicating with the outside world. The secret of the Yellow Wyrm Grotto-heaven had yet to be exposed, but if either one of them were to die, Cloudfiend Mountain or Po Cloud Lake's Nine Demon alliance would definitely launch a thorough investigation. When that happened, the Yellow Wyrm Grotto-heaven would definitely to be exposed. Many of the treasures within might be snatched away!
Therefore, capturing him alive was the best choice for the time being.
