No doubt, Malzahar is one of the best champions to go mid with. He can do a lot, and sometimes to only threat to him is an enemy who also plays Malzahar. He can spam his spells, get mana fast, silence the enemies and spawn those voidlings like a joke.
My favorite thing about Malzahar, besides the lore and the eye-candy skins is his ability to get mana. Malefic Visions infects his target's mind, dealing magic damage each second for 4 seconds. If the target dies while afflicted by the visions, they pass the curse on to a nearby enemy unit, refreshing the duration and restoring mana to Malzahar. So, what else? The voidling that is spawned after casting 4 spells will attack the enemy (Champion, minion, monster) with the Malefic debuff on.
Malzahar feeds on Ability Power (AP). Therefore, you need to get as much as AP you can. Let's see the runes you can use first:
- YELLOW: Greater Seal of Potency ( + 0.59 AP)
- RED: Greater Mark of Insight (+ 0.95 Magic Penetration)
- BLUE: Greater Glyph of Potency ( + 0.99 AP)
- QUINTS: Greater Quintessence of Insight (+ 1.89 Magic Penetration)
So, you now have enough AP to harass the enemy at early game. Now, the items list:
Doran's Ring (the standard starting item for an AP caster, must have)
The boots, are an obvious choice I guess: Boots of Speed -> Sorcerer's Shoes because yeah, you will need even more Magic Penetration.
The next item, depends of how much you kill your enemies. If you gank or you're successful dealing with your mid opponent, build a Mejai's Soulstealer as soon as possible, so you can stack some more AP.
If you are unable to get your Mejai's, get a Amplifying Tome, then build it into a Rylai's Crystal Scepter. Slowing down enemy champions always come in handy. Especially with Malzahar. Sometimes you'll need to slow down the bastard, for a successful Nether Grasp, Malzahar's ultimate spell.
Even though Malzahar can regenerate mana fast, there are situations when you'll run out of mana. Therefore, the items you should buy is Tear of the Goddess. First you buy the Tear, than with a Blasting Wand you build it into a Archangel's Staff. I had matches with two Archangels, the work as a charm.
For a late game, Rabadon's Deathcap is the best item you can get, so work on getting it. Lich Bane also gets the job done, so consider it, especially when you need mana and some slight protection.
Here's a screenshot from the Masteries I always use with Malzahar. Get Ignite and Flash as you Summoner's Spells.