"darius is a bad late game champion"

Who said that? lol

I have never heard a soul say darius is bad late game.

Old darius had a shitty late game.

New darius has a conditional late game. If he gets noxian might late game, the 200 bonus AD and insta stack is just as dangerous as it is level 1, moreso to squishies he comes across.

The reason darius does well late game because his squishies, as they get closer to 6 items, melt enemy frontliners, allowing darius to get a quick noxian guillotine on the front tank before running forward (maybe even flashing if available) with a channeling decimate so that he can spread his bleed fest to as much as possible and get one or more dunks before he too gets evaporated.

Decimate also has incredible heal potential late game, comparable to late game pre nerf vlad q when vlad is low hp. I have literally healed ~1500 hp as darius before, I kid you not, with a single decimate. Make vlad envious.

But like I said, his late game power is conditional, if he doesnt get noxian might he doesnt do much. If he doesnt land decimate heals he evaporates like any other tank/juggernaut late game.

TL;DR Darius is the only tank late game that can burst shit down after his backline sets him up to dunk the enemy front line. The missing hp heal on his decimate is also an extremely powerful sustain tool since his hp goes down fast. Where other tanks get evaporated, darius has the opportunity to get heals ranging from 300 to WELL OVER 1000 depending on how his decimate goes.