for those who are too ****ing lazy to find out for themselves
If you are 270-425 range from darius and you arent killing or chunking his hp then you are losing.
If you are less than 270 range or more than 425 from darius then you are either fully engaged or evading his reach.
If you are between 425 and 550 range you are preparing for engagement.
If you cannot defeat darius it is either because you fed him or he counters your champ. If you stay in lane and let minions die you can keep your level up and do your best to get gold under your tower.
If he dives you just run because if youre too damn lazy to learn this for yourself you got no business fighting darius with a disadvantage even under a tower. Just make sure you don't fall behind in level and invest completely in your champion's utility because your offense and defense will be weaker than normal, I'm not going to bother explaining why, obvious cause begets obvious effect.
Darius cannot snowball off minions alone. Sometimes youre better off letting the snowball melt alone. Go jungle or something.
Remember that the tower he keeps pushing at isnt such a big deal. Let darius take the tower in exchange for ganking chances. Eventually he will get it using this method which can sting a bit but you need to swallow your pride and get the **** over it. You werent even able to come up with your own strategy against him so let him have this first tower in exchange for not getting you which will allow him to snowball even harder.