So, if you don't know this, Malzahar might've been a cheese strategy during season 6, but that was over a year ago. Currently, Malzahar isn't really that reliable of an AP champion. As far as your recommended builds go, they aren't too great. For example, you don't really need a Tear of the Goddess on Malz. You should have plenty of mana sustain based purely off of Doran's Ring, Morellonomicon, and the mana restored from your E. However, if you do insist on getting it, completely finish it into an Archangel's Staff, as it will give you more AP overall, and once you have achieved 750 stacks, you will have Seraph's Embrace. Another thing, Lich Bane is a terrible item for Malzahar. While it may help with pushing and give your autos a bit more oomph, it would be better to replace it with a Void Staff. I would also encourage swapping Sorcerer's Shoes for Boots of Lucidity, as the extra CDR is much better than the Magic Pen for Malzahar, and since you should be building Void Staff. Regardless, good luck on the rift!