So this is how I play malphite and I have had enormous success with it. However playing malphite takes guts and knowing how much you can get a way with. This guide will be short and condensed with some tips at the end.

Starting Items:

-sapphire crystal
-1 health potion
-1 mana potion

Why you say? Sure malphite's passive prefers health, but with the extra mana, you can harass more, and the pots are extremely useful to stay in lane. ruby crystal doesn't allow for this.

Early game:

-catalyst the protector
-mercury treads
-Heart of Gold

Rush catalyst. It will allow you to sustain in lane for a long time, and benefits your passive with health. Mercury treads for the MR and tenacity. If the team is literally a ton of CC devoid AD carries, then go ninja tabi. Heart of gold will help you boost your gold gain even more and the health is too good to pass up.

By now you might have a kill or two or some assists, so from this point, you will gather gold extremely fast.

Mid Game:

-Sunfire Cape
-Banshee's Veil

Its hard to call mid game with malphite, but these are the items that make him play at mid game performance, even well into the late game. Malphite utilizes sunfire cape better than anyone in the whole game. He gains extra benefits from both the health and the armor, and the damage over time compliments his W and E skills very well. Banshee's veil is great for more HP and MR, but that shield it gives is great incase you need to get out of a bad initiation.

Late Game:

-Randuins Omen
-Atma's Impaler
-Abyssal sceptre

This may seem odd, but this is when malphite goes from tanky DPS to DPSy tank, if that makes any sense. You should have plenty of defenses at this point. Randuins omen used with your ult is amazing to slow the enemy after the knock up. Its a perfect item on malphite ALWAYS get it. With all the HP you have atma's impaler gives you more tankiness with armor, but also increases your attack damage. But malphite also scales with AP on two skills, abyssal sceptre helps you keep the enemy guessing on what defenses to buy. It gives MR as well making you tankier. the magic reduction aura makes you better and helps your team.

Alternatives:

-rod of ages
if you don't need more magic resistance, pick up rod of ages. It provides tons of health, and gives the AP you need. It will assist you more with atma's and your passive more. This choice is ideal against teams that lack AP damage.

-rylia's crystal sceptre
Not the best choice but, you basically will be perma slowing anything near you by %15 and it really stacks up well if you need the CC badly

-Shurelia's Reverie
This item is sub-optimal for my build, however it is still one of the best malphite items if you need some more team mobility. Makes your skills a bit more spammy. This coupled with randuins omen can make a fight yours easily. Great for a slippery enemy team.

-trinity force
All around spectacular. If Your final item just isn't cutting it, or you don't think anything else is enough, this is where you should go. this item has it all, and will do a lot to make you more offensive.

Since the new masteries, I have been messing around, and I like this one.

In this build you get ignite and flash improved. However you might also want to just go 9 into offensive instead of 4/21/4 for more brutal playing. I made sure to pick up the decrease tower defenses and reduced AOE damage. This allows malphite to quickly push a tower down and also saves him more in a team fight after he initiates. But really pick what you want. I like to get bonus gold on kills and assists, because with malphite I tend to get a lot of those.

These are pretty much tank runes. However you might want to replace the attack speed runes with something else, I just like them more to take advantage of his ability to do splash damage. I don't own many runes, so I can't say this is the best, but I imagine these would be useful.

Ignite:prevents healing when you want to combo for a kill, and the damage helps too of course. Exhaust or surge could be viable replacements for this offensive spell.

Flash:great for chasing. flash ahead, shard the enemy or ult them, and its a kill. Also, it makes for a great escape. Combo this with your ult for a clutch escape, and no one will catch you unless they are also malphite with flash. Replace with cleanse or ghost as viable escape mechanics.

When you push up to a tower hit W for increased attack damage, and the bonus armor will allow you to take tower and minion hits if you are close to finishing it off.

Malphite isn't great early game until he gets his ultimate. just farm the lane and shard the enemy champions so that they can't hurt you in lane or farm as well. Don't expect a kill unless the jungler ganks.

Last hitting is easy with malphite, auto attack the minion waves until your passive AOE damage gets them low and then hit E for multiple last hits. This can also be a great way to counter push a lane and then harass the enemy champion.

Malphite is a great solo top champion, just make sure to establish your place by bullinging with your Q skill, run in and pops some other skills and run out while the speed buff is still active.

Malphite can almost always get a kill at level 6. Make sure your shield is up, and you have enough health and mana. Once the enemy is about half health, combo with a R>E>W>Q or Q>E>W>R. If they throw on a health potion, or if you need more damage ignite them. You should then be able to kill them with another combo. It is safe to tower dive in most cases with catalyst or a health potion. But if you have trouble flash is there for a quick escape.

Malphite is one of the best initiators in game. Don't be afraid to jump into the fray, your team will folow once they see you take out a fourth of everyone's HP with a R>E combo. If you need to just use Q on the fastest enemy and you can get out quickly, or flash if even that isn't enough, but malphite can take a lot of hits, so you should do fine.

Once you get sunfire cape, pushing lanes is a breeze, your massive AOE damage will allow you to push hard and force the enemy to protect a tower or lose it.

If you are being chased by the enemy, use Q on a minion or jungle monster to gain a boost of speed.

In lane, bob in and out. Do your last hits and harass then back off, make sure your shield comes back up and dive in again, this should keep your health up in lane.

He's fast for a rock. Things will get dicey, luckily malphite is amazing at escapes. If the enemy has a rammus in powerball you can steal tons of his movement speed with your Q. Never be afraid to use your ult to escape. If you are worth as much gold as I hope you are, its worth using it to escape.

Eat BBQ chips and win.