I basically dislike everything about this build, but I'm so happy that someone else is using Nashor's Tooth, so I upvoted. My favorite build with her right now is:
Hextech Gunblade
Rabadon's Deathcap
Luden's Echo/Void Staff
Lich Bane
Nashor's Tooth
Bloodthirster
I'll run Mobo boots until I sell them for Nashor's or BT. I didn't think about using Nashor's before, but changing to more of a hybrid playstyle like this multiplies both her sustain and dps.

this build absolutely sucks first off i just played a game with this build and i was dealing less damage, and receiving more damage from a lissandra, i fed 8 kills because of this build, sure the regen is ok but thast what ur Q is for. Plus Triforce is utterly useless on her because of her passive
the more AP you have the more AD you will deal
Theres no point in taking feast in masteries because you use no mana
this build sucks dont trust it

This guide definitely isn't for beginners... with very little defense she's F***ed the instant she gets caught...

Tx for the info bro :)
I use the extra energy regen because the nasor's tooth gives me cooldown reduction, enough to spam more abilities without running out of energy.

Really interesting.I have my own build but I'll sure try the bonus energy out.I don't really suffer energy problems but this gives you an option to spam your skills without caring too much and that is what you can't really do on Akali since 2xcrescent slash takes you out of energy if u didn't mark the target before.