Wow... I still don't understand what the hell is going on in this story.
Basically, in the original timeline MC fell in love with the sword ghost (Siegfried), and when he died she used the wish granting ring to avenge him. And when she finally did, she died. Her brother the used the same ring and wished to be able to save her. The way this wish was granted is that the brother goes back in time and anytime MC dies he starts over, and through many loops he is able to go back even further and gain more strength. But fate is strong, and even if MC lives past a certain point, she will eventually be killed. The brother tries everything, including using similarly overpowered artifacts to prevent MC's death. One of these plans is the current timeline where MC is split into two, and this might 'cause some mistake in fate and finally allow for MC to live, but even the brother is unaware of what might happen next, so he gathered every powerful hero in this tournament to help him.