Be aware that Voidlings grant 12 Gold as bounty. If you die while having a Voidling summoned, it will not die outright but it will stay motionless and sometimes attack an opponent very close to them , they can still be killed to grant their bounty
Never underestimate Call of the Void. It is extremely effective at turning team fights, both damaging and silencing as many enemies as possible.
Call of the Void can turn a disadvantageous push from enemy team into a stalemate by spamming it on incoming enemy champions. Enemies who were damaged and silenced will think twice, or even retreat from the front due to the momentary vulnerability while the silence debuff is in place.
If there is an enemy who needs to cast his whole combo and escape with skill try to silence him after he is in range. He will be an easy target after it.
Casting Malefic Visions on an enemy minion that is about to die is a good way to farm minion kills or harass safely because of its chain reaction.
At rank 5, with about 100 ability power, it can completely kill both melee and caster minions at full health.
Malzahar will still gain gold and xp from anywhere on the map if Malefic Visions finishes off the minions. This is useful both to avoid being denied and to continue to farm aggressively all game long, but be careful as this might cost you gold and exp if the vision is blocked by enemy champions or siege minions.
Leveling up Malefic Visions early in the game is a great way to harass enemy champions without using any mana. Simply cast it on a wave of minions near the enemy champion and auto-attack the infected minion until it spreads to the champion. This results in around 50-120 gold, almost no mana lost (you might have gained mana), and the enemy champion being out of 100-200 health. At rank 1 it takes 6 minion kills to fully refund the mana cost. At all other ranks it takes 5 minion kills to fully refund the mana cost.
Against a single target (champion), Malefic Visions is Malzahar's most mana-efficient damage ability even if it doesn't jump, and is his only harassment method that won't push his lane.
There is a bug where two nearby Malefic Visions will not both propagate. Try to avoid casting a second copy in big minion waves.
Null Zone is a great way of zoning enemies as they realize it takes away a percentage of their health.
Unlike most burst mages Malzahar can bring down fighters without much resistance , as his combo is the most powerful in-game (balanced by the entire lack of escaping abilities) and offers the highest DPS in game during the 2.5-3.5 seconds in which most of it happens.
Remember that Malzahar is a combo mage (NOT A BURST MAGE, as it requires him to channel it), this means:
He has a massive power curve at level 6 and can flash-kill almost any laning opponent.
He is an easy prey to anti-combo opponents , such as Kassadin.
He has long cooldowns , by extra-careful during those and abuse of your Voidlings while you have no abilities , as unleashing a full combo will always get at least a voidling.
Malzahar excels at killing carries and mages on teamfights , as they cannot defend or attack at all because of Nether Grasp and they are too fragile to survive, but it is dangerous to do so when the enemy frontline is present and carries are more likely to get a Quicksilver Sash.
It is usually a better idea to use Nether Graspon fighters or initiators than on carries, as a full combo with QWER and assistance of your team can most likely take out one member of the enemy team from the beginning of the teamfight.
Using a Banshee's Veil is another good idea for more survivability and prevents your ultimate Nether Grasp from being interrupted by an enemy with a stun or silence.
Hextech Revolver is a good item as it will keep you alive with the spell vamp while you are using Nether Grasp. However, on his AoE spells, the spell vamp is diminished (33% rate). Farming minions waves with Malefic Visions and spell vamp item can restore a lot of mana and restore health.
Malzahar can be built as a pusher as well. With his Voidling, he is able to put out a considerable amount of damage on turrets. Don't be afraid to buy Lich Bane if you are feeling confident enough to push.
Malzahar has an unspoken potential as an AD caster due to the fact that Malzahar's voidlings benefit from his AD, and his armor penetration. This makes a spam-oriented AD Malzahar build fairly viable.
Youmuu's Ghostblade provides Cooldown Reduction, Armor Penetration, and Attack damage, as well as a handy passive that makes autoattacking more frequently a valuable asset.
To supplement the high mana costs regarding spamming spells, Manamune can synergize in particular with this build as it provides Mana and damage, which helps you deliver minions that are in turn stronger. Additionally, Muramana also gives Malzahar strength with his autoattacks, although it is advised to use Muramana's passive sparingly, as it will drain your mana just as fast as any of your skills.
Banner of Command grants his Voidlings 15% increased damage, as well as giving Malzahar AP for spell damage and armor and health regen for general survivability. This should be in most Voidling-centric builds regardless of an AD focus or not, for its valuable stat bonuses that any kind of Malzahar can use.
The Black Cleaver provides CDR, built-in penetration, and attack damage, while also giving Malzahar more incentive to autoattack, as your attacks will passively reduce armor for all incoming sources of physical damage, including Voidlings.
For this kind of build, Trinity Force allows you to augment physical attacks and encourage your spell-spamming while giving you light CC and and damage for your Voidlings.
Alternatively, Frozen Mallet has the same built in slow as well as health, but does not amplify damage as well as Trinity Force. But if you need a guaranteed and harder slow than Trinity Force or desire bonus health, then this is a valuable item.
The Bloodthirster can grant a spectacular amount of damage and sustain, and Malzahar is naturally good at farming minions up.
To make Malzahar's autoattacks potentially more lethal, Infinity Edge can grant you a potential for larger damage through critical strikes. Regardless of whether or not you're concerned with Malzahar's regular damage output, his voidlings will still benefit from the attack damage it grants.
Malzahar's abilities deal magic damage so getting more than 100 magic resist can severely hinder the amount of damage he puts out.
Malzahar's one of the (if not the) most powerful 1v1 champions in game as his combo is extremely overwhelming for almost any champion, because they can't benefit from any life steal or spell vamp during the combo, due to been disabled, in the other hand, he is pretty weak if long range crowd control or tank with long range gap-closer is present.
If you see one of your allies under the effect of Nether Grasp, you can stun or silence the enemy Malzahar out of the channeling and safe your alliles.
Be extremely careful about turret diving Malzahar even if he has very low health, he will just deliver the combo, while you are suppressed and getting killed by the turret
If you play as a tank, take care not to stand above Null Zone for too long or else the spell will devastate your health and can sometimes kill you if you're not too careful as it deals a percentage of your health.
Malefic Visions is Malzahar's main farming-tool and mana-sustain early game. If you stand next to a minion that has Malefic Visions on it, so that it jumps over to you and not to another minion, you can deny part of his farm early game, but beware that Malefic Visions and voildings still do considerable damage. This tactic is better used by high sustain champions with self-heal or huge shields like Galio whose shield allow to catchMalefic Visions and still get away pretty unharmed.