This build doesn't do a lot of damage until late game. It's meant for a solo top or mid play style. It has plenty of survivability and more damage out put then anyone would guess.

Pros
Survivability
Easy to learn
Hard to harass
Good CC
Good initiation
Can tank towers for day

Cons
Hard to escape without ulti
Weak against strong AP
Minion farm early game is difficult if pressured
Mana problems early game

Your ulti is great for ganking. You can move through thin walls and it give closing distance. Standing brush and behind walls out of site will cause get you the best situation for ganks. Walking in and out of brush making your presence known will scare back enemy's pushing lane, it's good tactic to use when your ulti is down and team mate needs pressure relieved.

Early game red buff is always good in any lane. Keep taking red buff as much as possible all game. Mid to late game if possible for wraiths and take enemy blue buff. Taking the enemy blue buff doesn't step on your teams toes and hinders your enemy teams AP user. You're weak against AP hold them back insures your progression.

As long as you are in the laning phase you are more then likely alone. In the event that your jungler comes up to gank for you let him take the kill. You are a late game champ, letting your jungler feed some allows for stronger ganks. Also, don't push lane. It makes for better and easier ganks. Your jungler will be more likely to gank for you if your lane isn't pushed.

When you initiate a team fight ALWAYS make sure your team is also willing to follow you. Always use your ulti to initiate a team fight and let your team know if it is on CD. Focus the AP mage first and get your AD carry to help you. Once they are down you will much harder to stop.

Between your E and the frozen heart the enemy AD carry's ATK speed won't be very high. Keep close to them to ensure minimum damage to your team.

Do not run from team fights late game even with low HP. If they are focusing you then your AD carry and AP mage will be able to max out there damage. It's better you die and all of them than your team die and you live.

Don't get greedy. You are not the only one on the team and every one on your team is just as important as you.

Using your Q to last hit minions while being pressured insures that you get some early creep score. Using the passive cleave from your W and then using your E to last hit multiple minions is good for quick minion farming. It works well to get minions off turrets or to help minions push lanes. After the laining phase don't worry about being focused minions, your granite shield can tank the damage.

Malphites ulti can move through terrain and surprise the enemy. This isn't just good for ganking. Ward the enemy blue buff and use it to go threw the wall and steal it. Keep timers on the enemy blue buff. It can also be used to escape. You run in a safe direction or through a wall away from danger. However, escaping through a wall blindly can be dangerous.

Your Q has a slow and is good for chasing. It also stacks AP damage an has distance. Good for a last as they try run. Good for early harassment on solo top or mid.

Malphites E is AOE and reduces ATK speed. Use it right after you ulti and try to hit the ad carry with it as it will nerf there damage.

The W increases the damage of your E and your auto attacks as well as gives you a passive cleave weather or not it's activated. This should be up as much as possible in a team fight. Once the fight is initiated this skill take priority over all the rest.