Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Itemization for Malzahar
Tip: When engaging your foe (the biggest nuke or the tank in a teamfight), throw out Malefic Visions, Null Zone then Nether Grasp the target while it is in the Null Zone.
Tip 2: When pushing the lane put Malefic Visions on the caster creeps first then Null Zone where the melee creeps will be in 2s.
Btw: Your AP tends to get around 600~ and after the second Archangel's Staff you will never have mana issues again: therefore, spam to your heart's content.
Last Bit: Sometimes if a match has an overabundance of chase enemies I buy Frozen Heart over Lich Bane. The Cooldown Reduction is just icing on the cake.