Rakan Visibility Exploit

I'm obviously not going to share the more intimate details of what happened since I dont want more people to be doing this and Im p sure explaining exploits is against the rules but just.

Ran into a 3made with a Lee Rakan and Xayah, and the Rakan kept using some kind of method to make it so he could instantly cast his w from fog of war on top of us.

IE: He would sit outside of visibility range, then E onto Xayah and W, and do so quickly enough that the flash knockup he has would be invisible the whole time until we were already knocked up and he'd only appear visible after he'd already finished the spell giving us 0 reaction time.

Has anyone else encountered this and how the hell are we supposed to have fun with the game when people are doing this garbage.