So I did some twisted treeline and I told my friend "how op would tank Akali be" and I made it and legit a ashe ult hit me and did not a bit of damage.
I went 24/1/5, so this build is pretty good.

This build is somewhat tanky,but with akali you still have to have a item or 2 that will give you some focus on ap, that's why some runes are ap.

At around 15 or 16, if you are around 3/4 of your build you will have around 3k health, and still will have tons of ap and pretty good attack speed too.

Pros- Akali is a super good Ap champ, even with all this tank, abilities will still do massive damage.
Ganking is safer, you can take alot of damage and be the tanky assassin.
You can now ult to kill enemy's under tower and not worry about dying.
Being at mid, you will be able to handle a really good person playing a Yasuo or a Kat.

Cons- From your normal akali build this builds Ap is alot weaker.
You may a feel a bit slower, but it's only because your tanky.
Armor Pent. Will hurt, your health is high but if your armor is gone you can't just Yolo in every situation.

I'm not the best leauge player, matter-of-fact I'm not good at all, but this build is so fun, mainly if you get fed.
I'm a basic leauge player, I've only been playing a month and just reached 24.
I main Shyvana Jungle, and a little bit of Jinx on the side.
On twisted I play Akali alot, that's where this build came from.
To End this off I want you to feel free to comment and give suggestions on items that could be different.
If you want to add me on Lol my name is "3cclusive" I'll talk to you about a few champions if your newbie too, even help you find your main.
Thanks for reading!