The number one spot belongs to a figure that is so powerful that his haki still echoes across time. Haki is not just about ...

Rayleigh has great control over advanced forms of both Armament and Conqueror's Haki. Although not as strong as an Emperor in his old age, he can hold his own against just about anyone in the series.

Observation Haki is one of the most powerful abilities ... not everyone may possess a Future Sight as advanced as the Emperor's. This raises the question of whether this ability helped Shanks ...