Or, her E. People under estimate that. I'm a cait main, and I'll engage with a net on them for a guranteed headshot, and then as they run away (slowed) I land an easy Q. In lane that's a trade that takes (typically) half their health, leaves me relatively close to my own minions, and only takes me half a second to pull off.
Now, this takes practice to pull off, and you have to manipulate the wave such that you can get your E on her, but if you do it successfully you take half their health for little to no return dmg.
Is it broken? No, I don't think so. It relies on landing two skill shots and manipulating the wave such that you can pull it off, but when it works, it's devastating.
If I'm dueling 1v1, in the middle of river (For an example) I'll engage the same way. As soon as my Q fires, I lay a trap between them and me, and another one right after diagonally downwards from the one I just laid and kite backwards. If they follow me towards my traps, I walk forward and place one behind them and they die.
If they try to run away, I just auto them to death as they are already around half health (And typically the E slow has made it very easy for me to do this).
A little off topic, but if you're lucky. Auto, E, Q, Auto (Sometimes x2) into R is almost a guaranteed kill if I'm at least equal with the enemy ADC. Depends on their build and champ of course.