PLAY HIM IN THE MIDDLE LANE
I cannot express this enough, he rapes in the mid.
He is better in the mid for many reasons such as:
- his ulti makes him less prone to ganks
- he is possibly one of the best farmers in the game, Q and E
- hes an AP carry, just put him in the mid for gods sake

Abbreviations you need to know

MV, malefics - malefic visions
NZ - Null Zone
Scissors or CotV - Call of the Void
lazzzzer, NG - Nether Grasp

all the others like mia, gank and **** like that you should know or else you shouldnt be reading this guide

I use flash and ghost for summoners simply for the Surprise, Chasing, Escaping capacity's of the skills. Flash, Ignite are also a viable option you just have to watch out that your ignite has a shorter range than your ulti, this means you can accidently cancel your ulti by casting ignite on them as well

Farming - when the first wave of creeps come wait for the first targeted minion to get to half health then pop MV on him, when you are this low level always try to hit the creep with malefics on because it isnt strong enough to kill the creep by itself.
Mid - Late game you will be popping malefics on the melee creeps and scissor the range creeps (try to get them in the line).

Fighting
whenever you are going for the kill and he is has a reasonable amount of health pop NZ and then lazer him while he is on the pool, even if he is on lowish health, BECAUSE "overkill is underrated"
Sit back in team fights as usaul and just spam spells, lazer their carry and destroy him with your MV and NG, use scissors if necessary and then put NZ under the tank, it ***in hurts.

VOIDLING - if you want to harass your enemy really bad and their not goin anywhere wait for your voidling to be ready and pop MV on the hero. at lvl 7 i have taken ashe to half health with this combo.
another point is sometimes its better to wait till the voidling is at its full size as it does way more damage this way

also to remember that your scissors has a silence and it has larger cast range than the rest of your abilities, keep that in mind when chasing

Malzahar's ultimate - Nether Grasp is one of the most powerful abilities in the game. he is the only champion that has a ranged suppression, this suppression last for 2.5 seconds. One of the best places to use this ulti is if: When you are playing in the mid and someone tries to gank you like a xin or an udyr than get them into the range of your turret and pop ulti on them. This well cause them to get hit by the turret about 3 times. at lvl 6 this will generally result in a kill and you staying alive as they cannot pop ignite or any other summoners while suppressed.

PROS
- awesome AP ratio
- tons of damage
- plenty of spell pen
- tank shredder ability
- LAZZZZZERRRR EYES!!!!!!!
- silence

CONS
- squishy
- voidling is uncontrollable :(
- bit of a mana ***** if you suck at using MV
- he's 6300 IP

all in all this guy is probably one of the best champions out there atm.
If you think there is anything more that i should include in my build please feel free to leave a comment below thanks.