Hello and welcome to my first Guide here on Mobafire - hope you like it.
I have been playing Malzahar alot since he came out, and I always tried to play him with a AP Build, BUT i noticed that he scales like hell with the Hybrid-Items. With this build the Rageblade is your Core Item, so your goal in teamfights is to bring up your stacks quickly to nuke with your spells like hell.

Pros:
- still makes a high amount of damage when out of mana.
- you won't be focused, since the enemy team will think you are a noob - that lets you stack your rageblade up quickly.
- The enemy team cant counter you that easily, because you do both, magical and normal damage.
- You will own in early game.

Cons:
- You can't autoattack while you do your ulti, so you lose alot of dmg. using it; So don't use it, unless you are in a team fight.
- Fast champs can easily avoid your damage, because you have to autohit.
- Could feel a little bit weak in the late and mid game.
- You need a lot of farm to fulfil your itembuild.

I take Magic Penetration Marks, to do greater Damage with my spells, aswell with my Malady and the Wit's End.

The Armor/Magic Resist Zeals/Glyphs simply give you he so much needed early game survivability

For Quintessences i take flat Attack Speed, but flat AP or AP per level would also work, if you prefer them.

At first i get the Boots just in case i got a hard harasser on my lane. It helps alot in avoiding dmg. (healpots for the same reason)

The first time i go back then i can usually build my Sheen + the attack speed boots. this will really help you harass on your lane with your 'E' and autoattacks.

The next step is to either fulfil your Lichbane or buy the Rageblade. Normally you dont got enough Gold to buy the Rageblade, so you have to take the Lich Bane.

Nunu:
It's always great to have Nunu on the lane, because he can give you attack speed with the 'W' and slow your enemies, which lets you autohit better.

Warwick:
Your ulties harmonize well, as they are nearly the same and he gives you aswell the so much needed attack speed.

Janna:
Janna is a great all around Supporter, but the greatest thing about playing with her, is her shield, which also gives you some Attack Damge to improve your autohit harrasment.