how to counter akali's Twilight Shroud ?

Damage per seconds reveal briefly the position of stealthed champions

but darius is garbage atm

Just drop a pin - oh wait.

Unless you have a taunt, a way to knock her out of her W, AoE damage or the ability to grant true sight (like Lee's Q), there's nothing you can do.

If you don't have a reveal, you can't.

Just have to be a champion with AoE damage and hope it's hitting her. Not really a counter, just trying to do what you always do but blind.

Sweeper.

Sweep.

Or just aoe and make her pay.

If you have sweeper you can use it to see where she is. If you have any dot abilities, AoE, or can hit her with a large skillshot, then shimmer will tell you where she is. If you have an ability that grants true sight like Thresh Q, Morg Ult, Kayn Ult, etc. you can use it to reveal her. You can also position yourself around her shroud to block off the place where she is most likely to go to escape to force her to take a less advantageous route and kill her that way. The radius of her shroud is very small so you know exactly where she is.

One of the first rules of League of Legends is to not fight Akali in her shroud so if you stand right in the middle of it, then you are guaranteed to lose the trade/die.