What's so strange about it?
Rab Cap makes sense for more damage, Zhonya's for survivability, Gunblade for more passive and damage and the active along with the spellvamp, and GA for more survivability
Really, early on all you need on akali is something like a Revolver or the gunblade itself to 100%->0% most enemies
I build akali revolver, rylais, lichbane, gunblade, GA, void staff, and almost always use merc treads. I could see swapping rabs in there for something, but I still wouldn't buy Zhonyas. The 2 seconds isn't going to buy you much in a TF, I'd rather R to an adc or an outside minion.
Early on all you really need is revolver to have pretty decent lane sustain. I think gunblade could be pushed off til later, ls is a wasted stat on her.
I'd get rylais but dont think its necessary or all that good of an item
Normally im able to stick to an ADC like glue anyways so the slow doesn't help much
Zhonya's isn't a bad item on any AP mid, the 2 seconds can really be effective, it adds the damage, armor, and the active which make it a very good situational item, id normally get an abyssal before it or instead of it but most of the damage was coming from the Garen and nid tbh
so the armor came in handy
and the Gunblade is still good early on, Like I said with a gunblade and T1 boots I can 100-0 people on the enemy team easily
Lichbane can be good but it isn't necessary
And I do build mercs on her, but only if CC is a problem