Hi i'm killogher and i play akali from sezon 9.This champ it's powerfull after one item and boots. Now i present my guide on akali.
1)Up to level 6 try to no spam abilites because you have just 200 energy and you risk die when enemy jg come to gank.
2)In teamfight try to focus only adc because you can give one shot with R E hit Q and after press R for repositioning with your team.
3)Don't rush because, if you take stun you die fast just waiting for the moment.
4)Don't just randomly shroud for movespeed and try not to shroud at full energy unless you are in an emergency where the enemy will kill you and you are trying to escape. For example if you get ganked by an enemy, sometimes you don't have time to spend energy by using your Q or E, and you will need to immediately W. That is perfectly fine. My callout is that you don't just walk up to an enemy and then shroud at full energy. Try to throw a Q out first before your shroud.

1)Up to level 6: Q hit W Q hit E hit and ignite if he didn't die
2)After level 6: R hit Q W hit E R
3) R E hit W Q R

Oblivion Orb and Morellonomicon are really good items, but you only want to build Oblivion Orb early if enemy has a lot of healing and upgrade into Morellonomicon later on.

With the Akali changes for magic damage to E from physical, Akali no longer benefits from building Executioner's calling, since her Auto Attacks and R1 (First Ultimate Cast) is the only physical damage she has now. With the changes in Season 11, having grievous wounds for 800 gold is a huge help for Akali since it helps against champions that have lots of healing like Sylas, Nunu, Soraka, Yuumi, and etc. I would fit this item into the build and replace any non-core item when your team needs healing reduction. I would first build oblivion orb to replace any non-core item when your team needs healing reduction. As a late-game I would upgrade to oblivion orb because the only additional benefit you get is additional HP and AP as well as the healing reduction is increased to 60% if they are below 50% HP. My personal opinion is to hold onto the Oblivion Orb and build other damage items first and then upgrade to Morellonomicon later in the game. If you are about to have a big team fight and the only thing you can buy is a Morellonomicon, then I would upgrade the Oblivion Orb to Morellonomicon.

At level 1, you have to respect her range and damage. If you walk up to CS or trade, she will try to harass you. Try your best to bait out and side step her q, and then you can walk up to Q her or hit minions.
Major thing in laning phase is not overtrading without your w or e, if you think she will stun you for sure, try to W as it is going off so that you are stunned in your shroud so she can't target you.
Try your best to dodge her stun with your e, or even R.
At level 6, you can definitely all-in her and kill her, assuming you dodge her stun. Once you hit 6, this is where you start winning lane because you can just all-in her everytime your ultimate is back up.
Buying merc treads in this match-up is a good idea if you are having trouble surviving.
She WILL ALWAYS poke you down everytime you walk up to CS, and when you try to engage she will stun you. This is where merc treads and fleet footwork are really good. You can sustain in lane permanently and then when she is out of mana, you basically take lane priority and start playing more aggresive and control the lane.
Respect her damage mid to late game, since the current Akali build doesn't optimize for magic resist items, she can basically 1 shot you if you misplay. (Try to also Zhonya's hourglass her ultimate)

And don't forget have fund and good luck.
I hope you like my guide if you like give me +1