Now this is a very strange malphite build to see, doesn't it?
Well now don't be like the guys: "this is not the usual build = it sucks"... give it a try please.
This Malphite is used mostly for tanking high dps champions early-mid game and to tank everything mid-late game, don't wish to net a lot of kills, just assist, you'll see you'll get hard to kill.

Now for the runes, i use flat armor seals because i want to tank much more than just my items.
Then i put flat magic resistance glyphs because the magic resistance at the beggining is not too much sice the first item to magic resist you're getting is Guardian Angel... and it takes time to farm that, so we use this glyphs to boost our magic resist early game.
For the quintessences: movement speed quintessences makes our groun slam to hit much more often fleeing champions since we're maxing seismic shard late game.
And for the marks, i take attack damage per level marks, because we don't want too much attack, but we cannot get short on it if we want to solo someone and our skills are in cooldown or we're in mana problems.

For the masteries: i take 0-21-9
The tenacity and all the other protection masteries make us a little bit more tanky in all the fight, along with mender's faith, that reduces Heal cooldown, so we can use it often early game.
The Utility masteries are more of regeneration that we all need, along with insight, to ensure kills or ***its if our ally has mana problems.

We max ground slam at first, because it gets a lot of bonus from our armor, and attacks in an area, just what we need in team fights.
We take a level of seismic shard in level 2 because of the great speed steal that can make us ensure a kill, we don't level it up more until late game because we don't need more speed steal and we got the things getting damaged by our ground slam.
We max Brutal Strikes next, because we NEED the armor we get from this, always use it before you use ground slam in an enemy champion, plus it helps to farm due to his tiamat-like passive.
The top priority and the best skill from Malphite is unstoppable force, we can use this in many ways that I'm going to tell you next in the guide.

We take heal for any unconvenient early game, and almost every person gets ghost or exhaust that can be of use for us to net the great ground slam, then, if our friend is damaged, we use heal mostly to heal him, but we can use it to heal and save us from dying of course.
We use clarity for our great mana problems (you know, 2 ground slams and 3 seismic shards in early game is a hit in the nuts to our mana), and for netting a kill or two by assisting our teammate regenerating his mana.

Pros:

It's a very tanky champion like this, you can, at the best, tank three simultaneously.
It has a very good assisting capacity, making you loved by your teammates.
Very good sinergy with ground slam, shattering our opponents quickly.

Cons:

Doesn't attack a lot, making solo fights very, very, very, very long.
Doesn't net a lot of kills, almost everything is an assist.

Seismic Shard:

There are two ways of using this: for enemies chasing, or for safe escapes.
Chasing enemies: Save your seismic shard to the last moment, so if an enemy is escaping, you can slow him the necessary.
Safe escaping: If you think you won't survive a fight, or even a solo fight, you can use your seismic shard to steal speed, so the enemy will never get to you (unless is a Master Yi, Sivir, or Dr. Mundo with ultimate active, ghost, and a phantom dancer)

Brutal Strikes:

This gives you a lot of chance v.s. two champions simultaneously by raising your attack A LOT along with your armor. ALWAYS use this before using Ground Slam, sice it raises your armor, giving it more power to kill by your hands champions.

Ground Slam:

Just a tip: NEVER use this behind a fleeing champion, you will never hit him, it has a casting time, and before you hit the ground, the enemy fled. Use this always at the side of the enemy.

Unstoppable force:

This is Malphite UNIQUE skill. You can use it for this methods:
Initiating battles: If you see a lot of enemies together and your team is behind you, use brutal strikes before the battle, then start with unstoppable force, and when you get there, use ground slam, along with seismic shard to the weakest enemy, so your team can take care of it quickly.
Escaping: If you know there's no enough time to seismic shard the enemy, you can use (sorry... waste) your ultimate over a wall to a safe area, escaping from the enemy.
Taking kills: if you are in a battle you know you'll win, do the usual, and then, when the enemy doesn't expect it, use your ultimate to take care of it, and, if you're lucky enough, initiate another battle.
Finishing battles: if one, two or even three enemies escaping together, you can use unstoppable force along with ground slam to take care of the group, giving to yourself a lot of kills like this.

You should start with cloth armor and some mana potions to use your spells more frequently, specialy if you want to farm a lot in early game. If you odn't want to farm, but to pull (don't push so the enemies advance and you can gank them), start without mana potions, to save for completing ninja tabi. With ninja tabi you should be able to engage enemies even if there are a lot of creeps, because your masteries and ninja tabi will make the creeps (minions) to not hit you a lot.

At this point of the game you should get some kills with your teammate, or assists. With the feed or farm, buy first chain vest and then, or you complete thornmail, or if you are extremely fed, buy guardian angel, don't be afraid of dying with your guardian angel in teambattles early-mid game, or at least, if you're not afraid, don't run, try to net a kill before running. After this, get thornmail before the **** sings, it is very useful.

Ok, by this time, your teammates have to be loving you... LOL no, by this time you should have at least the negatron cloak. Let the battle progress as you kill and ***it more, as long with destroying turrets.

You should have killed and assisted enough to have all the proposed items in the guide, and, if the enemies are THAT good, you should tank two or three simultaneously, and assist in every battle with your precious ultimate skill. END GAME - VICTORY.