This is my Malphite build. I build him as a tank mostly. This build is ment to either initiate the fight or save the carry. Like a good tank should do. Save the carry. Dont qq cause your a tank and you died. As long as your team comes out ahead and your the only death all is well. With this build you have the abality to slow down the team incase of a retreat and still be able to get away. It will take at least 3-4 people to even come close to kill you and thats only with some really good cc.

I usually go with teleport and flash. teleport cause it is the ultimate pusher abality. Also it helps with saving turrets. there should be at least one person per team running teleport. It always you to solo lane (if need be). Malphite I find is a great laner. He can harrass well and due to his passive he is extreamly durable. I'm not saying he should solo but he can.

I run flash for obvious reasons. I find it helps dissrupt the opposing team if they decide to jump on you or if you run in to save the carry. Gets you great distance away from the opposing team, or to catch up to one person and use your shard to slow them and speed yourself up. Fun thing to do is run in have the team target you flash, ult. they will never see you again. Great way to leave them in the dust and waste their time and save your carry.

For runes I run standard tanking runes. flat hp q's, hp per lvl marks, armor per lvl seals, and mr glyphs. nothing fancy but gives him early game advantages and some mid-late game help.

As far as items go I put down recomended for him. giving him a good base of mr and armor. There really isnt any order to go with. It is all based on the opposing team. This is usually pretty standard for most. Gives you plenty of hp, armor, and mr. For the most part I get the aegis and merc treads first. As for the thornmail and sunfire it depends on if they have atk speed dps or not. It is more of a specific item.
This is a great build for ranked or casual play.