same way all assassins do my dear friend.
All assassins hunt targets that are isolated to some degree, by flanking behind and killing them.
In team fights, all assassin are having a hard time closing the gap to the carries due to their high damage and pealing from their team.
The "get in range of cait", is a valid argument you make for every assassin, AP or AD in late game and team fights stage.
While its more straith forward for someone like Akali or Katarina. Evelyn has an easier time flanking the enemy team due to her invisibility.
Which means, she will be either on a side or behind cait. And she will close the gap by running towards her once the team fight starts and cait pays attention to other targets.
Because you join a fight after an initiation starts, the adc will often hav a small delay (0.2-2 seconds) before they notice you engaging on them from a flank.
And once more, because of Eve's ability to sneak past normal wards, this means the enemy will have a distance of 700 units between themselves and Eve before they see Eve.
Which is enough time for you to surprise charm and try to burst the adc. I'd also like to say that your Flash E is instant and very hard to react if you do it when you are in range of it. Meaning, the adc can react to your flash, but usually they do not have 0.1s reaction time and they get charmed, which gives you enough time to execute your burst true damage combo ;)
Also, mind you. By the time you finish the
combo, you are not in the late-game team fighting state. You can at best expect cait to have IE and Runnans done, and maybe tier 1 boots.
Its much more easy to suprize and attack the enemy carries in alone positions in these conditions.
I do that almost every game when I do play assasssins.
Which is why
helps a lot. You can set up vision and see the enemy being alone in their own jungle, heading towards a lane, and maybe even have a lane ward to make sure there's nobody behind them. And this sets-up for very easy kills.
While vision and getting seen can stop assassination attempts. Vision and seeing your target alone is also what enables assassination attempts ;)
PS.
Eve's Q has 800 range.
Her camouflage has 700 range.
Which means, you can Q a target while you are invisible, while this will reveal you, you also are giving them very very little time to react.