rylai's is an amazing item on malzahar, giving HP, AP, and a slow (which is wonderful with Malefic Visions) and makes for a much better item to grab than GA. Grabbing Will of the Ancients is good, but in order to make it work, you need a bit more burst and, more importantly, more CDR, so you can consistently keep the damage up. Nothing helps a team fight like burst + constant damage. I prefer to grab Morello's Evil Tome to Archangel's Staff because the CDR is much better on malz than a large mana pool. With the bonus effect to Malefic Visions, Malzahar does NOT need a large mana pool.

You speak of caster sustain, and opt to gain bulk items. Yet, oddly enough, you have no rylai's (not that malzahar should, just simply listing it for the bulk) and you don't even MENTION a Zhonya's....wut?

I agree with Yarda. Your build stresses on a lot of sustain and survivability but I do not think it is effective on Malzahar. Malzahar needs to be able to burst an enemy carry from 100% to 0% and allow for his Malefic Visions to jump to another enemy. I feel like with this build you may be able to live longer and possibly stay in a fight longer, but you won't be able to turn a 5v5 fight into a 5v4 fight with one burst and if a fight goes bad all of that sustainability will not help you because of your lack of damage (in comparison to the opponent AP caster).

Perhaps it may be more effective if you swap the order of how you build your items. Stress damage first and then sustainability/survival.

-1 from me... you might have good sustain, but when teamfights roll around, you will do no damage compared to the enemy caster, cause while you have boots and a will of the ancients, he will have boots, a ring and a needlessly large rod (for instance).

That means he will have more damage, more health, more mana regen. You will have spell vamp. One disable and you are gone. Same goes for him, but if you both manage to throw your spells before you die, his will be stronger.