I don't like that you're judging the build purely off theory...
I've won many games with this build... And i just won a 4v5.. killing their 20 leviathan stack cho without a scratch =p

This build is for massive alpha + does well in team fights i am very intimidating and can hold up well against most champions.. Possible problems with champions such as olaf but you have a better chance with this build over others.

It's different and it scares you ;)

^ Agreed with everything he said.
AS quintessences are lacking for malzahar. Trying this out will not work because of...
1) Lack of AP. Nashors and Gunblade give 55 AP each. Rylais and Zhonays give 200 AP into total, if you include the 25% extra AP passive, thats 250. Almost as much as all your items combined without including Archangel's passive.
Malzahar is not made to backdoor. He's a VERY squishy champion as you can see. You cannot backdoor with this build because you don't have any items that increase health or armor which means he'll attack a couple of times then leave before being caught up in a gank.
Not a very good overall build imo. -1

So I really like Deathfire Grasp now that I've tried it. However, the Nashor's Tooth and Hextech Gunblade really won't do. Your build really really lacks ability power which cripples Malz in team fights. Multiple Archangels are no good because the mana stacking property from archangels is unique. Your build only has like 300 ap at level 18 which is terrible.

As for the Nashor's as another source of CDR, there's no point of getting tons of CDR if you don't have the ability power to back it up.

Malz isn't supposed to be a tower pusher. He shines in team fights where his massive nukes and silence kicks everyone's ***. The AD and attack speed you get from hextech gunblade and nashors is useless.

You're supposed to use Malz for his awesome damage output. Trying to make him do anything else is a waste.

This build would only work against noobs. Not gonna rate this build down but you should consider going a heavier AP build like getting rylais or abyssal scepter. Also, z-ring is a must for squishy Malz, I'm surprised you don't have it.

Thanks ^^ yeah try it out, he's great solo and in team fights. Plus it's easy to backdoor towers because of his decent output.

Wow, I just posted my own Malz build and this one seems weird and crazzzzy in comparison, barely any AP. I like your ideas though, I wanna try it out and I'll come back and let you know what I think.