In Black Clover, people has mana and ki. Mana is an energy source for magic and ki is.. well, that's what I want to ask. We know Asta can sense others through ki, but is there anything else? Does ki give people some power like in Dragon Ball? Is knowing it useful for any other thing? How does ki work in Black Clover?
Ki is a special kind of natural energy (Originating from Captain Yami's homeland), which is very different from mana. Unlike mana, all living and non -living things give off Ki when they move.
In other words, the ability to sense Ki, gives individuals the ability to sense attacks by people and projectile objects. Also, the fact that Ki depends more on motion makes it useful in detecting things which have no mana. An example is anti-magic; since Asta normally has no magic, Mages who sense thier surrounding for magic will be unable to detect him, however, using Ki Asta wil be able to detect his opponents, their attacks and also how much anti-magic is circulating through him.
Further training in Ki could even help predict enemy attacks and in certain cases tell if someone is lying.