Yasuo and Vi ult
Not sure if its suppose to happen but when yasuo knocks vi up to ult she can ult while knocked up to prevent yasuo from completing his ult.
4 Comments
Chances are, Vi had started the casting time on her ultimate before getting hit by the knockup. Basically, almost all spells in League of Legends have a casting delay; this is usually a 0.25 second delay between pressing the button and the spell taking flight. This is different from Channeling, because a channel can be interrupted with the appropriate hard CC.
So it's entirely possible that she targeted Yasuo (or someone else on his team) while the tornado was in flight, so that once it struck her, she had started her ultimate, which isn't interrupted by CC, so the rest of the knockup's duration would be wasted during her dash's travel time.
It could also have been a bug. Considering I didn't see it, I don't know the exact timing of the situation you witnessed. But it's entirely possible that she just timed her ult perfectly.