The early game is simple. you farm when its safe. I dont even bother to poke until im level 4 so I sit and soak exp until the wave pushes in to the tower and then i cs there. The goal is to not die and feed before you hit 6. once I hit 6 I look for a roam opportunity top or bot which is why I buy mobility boots first item with the waterwalking rune. This is what makes malphite mid work because the ganks i provide help get the team ahead early. If there are no roaming opportunities I try and poke down the mid laner until I feel that i can one shot them with my ult.

Malphite is fairly useless unless you have his ult up to one shot their carry or find a pick. This is why ability haste and ultimate hunter are so important to have. He cant really do much after you use the combo which is why I normally don't bother with getting zhonyas.

At this point you will be able to one shot anyone for the most part. If you use vision to find a good pick it can win games. Otherwise I look for multitarget ults or save my ult to peel for carries on the team.