Strix invisibility is good and gives him advance agnist any flankers trying to kill him but if you are playing as flanker take illuminate and take care of him easly when he cant hide from you
when you see trix shooting towards you and getting invicible try to shoot him(and make him vicible again after 500dmg)spray/shoot/splash dmg near the place he just turned his stealth on
Pick champions who are midrange or short range since strix will have to move his scope much more to keep up with you. Good champions are Skye, Jenos, Viktor and Tyra. Since they have massive DPS short range and their drop off is not that bad.