Edit from original build post [02/21/11]

Early Game:
Mana regen is HUGE early game. Focus on harassing as much as possible and don't be afraid to use to ignite on someone if they only have 1 health pot and use it. Try to start harassing @ level 2 Shard which will be at Lvl 3.

Early/Mid Game:
I personally like getting glacial shroud by lvl 6 because of the extra mana/armor/CD reduction, especially for your Ult.

Building Progress:
I personally don't like building Malph as a tank with almost all health items, try to focus on gettin armor and MR resists. I do get sunfire for the extra health and armor and the passive is just an added bonus.

Late Game:
At late game almost never use your ult in 1v1 situations unless you have visual on their team and never start a team fight unless your ult is up, or very close to being up.

Conclusion:
Malph is stupid OP in the beginning, especially if you are top solo. Focus on harassing early game as much as you can. Lvl 6 jungle ganks work like a breeze so try having ur jungle come gank every 3-5min in your lane and coordinate your stuns. If you are top/mid solo and playing against a mage or a weakling, it is not a bad idea to get 2 dorans rings early to maximize harass.

Hope someone out there likes this build! BTW I am a 1550 elo player, and so far this build holds up in ranked games with little problem.