For me, It would be Astraea.
Her Ability is called Ellipsis, which allows her to foresee segments of a future and her ability always creates the best outcomes and shows it to her. Making her nearly unstoppable during fights with opponents, as she is always multiple steps ahead of everyone.
However, this doesn't mean that she is completely unstoppable, as she cannot change "fated events", events that are destined to happen, no matter how much Astraea foresees and changes segments of a future. Fated events affect every person, as long as they're bound to the circle of fate, wherein everyone is encapsulated in.
It's like being an editor on a script, being able to change the script to your own liking. But there are some segments to the script that the director (or in this case fate) interferes with and doesn't allow you to change that specific segment to the script no matter what, and no amount of changing the script will ever prevent that event from happening.
However, for the ability to work, she has to be blind in both of her eyes for the best effect. This is why she made an offering wherein she blinds herself in both of her eyes, in exchange for her ability, Ellipsis, to be always active within her instincts. This doesn't mean she can't see anything though, as with Ellipsis, she can see segments of a future that are about to happen, but the world around her happens as normal. It's like separating the audio and video of a character talking in an editing software, wherein you take the video (Astraea's segment of a future) and play the audio (the present) 10 seconds after the character starts talking.
There's also a lot of complicated stuff about fate/destiny, but I don't feel like elaborating those so I'll just leave it there!