Its important to note this Akali guide is for a very specific Akali playstyle. The summoner spells are in my personal preference order. I do not reccomend taking the first 2 suggested summoner combos if you are not an exeperienced Akali player.
Akali at her core is not a burst assassin but what i like to call a " Burst Damage Over Time (BDOT) " fighter. This concept will be elaborated on further in the guide.
Barrier - Shortest CD on laning Summoner spell in the game - 180 Seconds : Provides higher defensive usable HP than heal and is not negated by ignite and doesnt leave Akali with a heal debuff.
This means Akali and aggresively lane trade negatively regardless who the match up is with. The low barrier CD means you can use it generously throughout laning phase from minor trades to escaping and baiting tower diving ganks.
Ghost - Shortest CD on laning Summoner spell in the game - 180 Seconds : Provides more distance covered than flash in extended fights, lasts 10 seconds and can manually run up to proc Q instead of blowing a R ult.
Top lane is the longer lane on the rift. It also means that if you're pushed up you're more susceptible to ganks. Ghost provides the gap closing and escape needs of a late game and early game Akali respectively.
Again, the low CD of ghost means you can ghost in shroud and go for some Q proc trades while in W shroud in lane and use it again once you have kill potential.