The Great Emperor Became My Shield

Plot Synopsis

The male protagonist is reborn as the old ancestor of a secret family. He awakens a system whose function can only instantly kill Great Emperors, so he has to stay indoors all the time. As time passes, more and more powerful people covet the resources of the male protagonist's family and are eager to challenge him. And whenever the male protagonist is about to be instantly killed by a powerful person, a Great Emperor will come to the rescue and then be instantly killed by the male protagonist.