As weird as it sounds I believe Malzahar is able to become a very interesting support, mainly because of his Q and R. If you have played malzahar mid chances are the lane went two ways, you stomp the enemy mid laner and lost the game because all the other lanes are useless, or you ended losing mid lane and became a peel mage. Therefore Malzahar support becomes a viable strategy, since it removes the "I can't carry as Malzahar problem" and you take a supportive role with one of the most annoying ults in game, so you can feed your carry.

The objective is simple, you must make the enemy team want to buy any form of qss and focus you to enable your teams damage or make them make mistakes. You must know that feeling of being powerless against a fed opponent or that "I was cc'd for the whole fight". What both of these feelings do is what makes you start to play poorly and destroy your mental, so that's what you are going to be doing to the enemy team. Be as Obnoxious and annoying as possible.

Tips.
Stay close to your carries and peel for them.
Use W for tower damage only when a cannon minion is present since towers prioritize targeting summoned units like voidlings, heimer turrets, elise's spiderlings...

Chances are you think I made the build while drunk, but no, everything in this build has a purpose.

-The support item(this one is tricky).
Personally i like to go with the relic shield instead of spellthief's edge, mainly because of the execute minions property it has (i know malza's E also executes) and the fact that if abilities kill a minion will still give the gold to your carry. I don't go with the spelltihef's mainly because it pretty much forces you to use a lot of mana to obtain the gold early game and also spamming abilities means pushing the wave. That being said, if you think you can work with spellthief go for it.

-Ionian boots.
This one is a no brainer, they allow more spam ob abilities and summoner spells.

-Hextech rocketbelt.
Simply for mobility, malzahar is an immovile champion, therefore this item works great on him, since they allow to catch an opponent and R them or to reposition.

-Axiom arc.
When you see this item you might instantky think it's either genius or trolling. This item will allow you to at least throw two ults in a teamfight as long as some enemies die. Or it will at least make you have ult almost all the time soon after a kill.

-Morellonomicon.
This item will apply grevious wounds for the full duration of your E. Buy the oblivion orb when deemed necessary and finish this item lastly.

-Archangel staff.
This item gives a lot of cdr and mana so it's very useful. Try buying the tear on the first back and finish building after axiom arc.

-Demonic Embrace.
This item is built if you can sell support item and afford it or if the enemies don't have enough healing to make morello effective.

-Mikael's blessing.
Odd item for sure but just adds to your supportive capabilities.

Malzahar's combos are very hard.

-Flash + R: This one is very hard since it involves pressing two buttons which are very far from each other in the keyboard.

-Protobelt + R: This combo is harder than the other since you have to use an active item.

Jokes aside. Malzahar's E duration is refreshed if he hits Q or R therefore to maximize damage you should do E > W > R > Q. Try to start the combo with one stack off your W or at full stacks to increase the number of voidlings summoned, therefore increasing damage.