I'm Actually the Demon Ancestor

Ethan Blackwood transmigrates into a fantasy world as the infamous Demon Ancestor, just as righteous sects launch their crusade. Summoned to fight, he discovers he inherited none of the original's power. He's completely ordinary! With death looming, Ethan has only two things keeping him alive—his acting skills to bluff the ancestor's reputation, and when that's not enough? Thank heavens, the System finally kicks in!