Malphite is a great counter to most mid champs. he can sustain long in lanes and his q if used wisely will give you several kills. What I recommend doing is keep using Q on ur opponenet. Once level 6 unlock your R. Keep damaging your opponent until the have about 4 maybe 4 1/2 bars left then R in W E and Q while stunned and ignite for the sure kill and do this several times. Build armor and magic resist with the gold earned and you will become unkillable.

dont be afraid to start a team fight by hitsticking some bks.

Malphites ult if used correcrtly will give him the upper domance against opposing enemy tanks. His Q is also good for chasing solo enemies for it gives him speed and takes the eneimies speed. His E can help in team fights. It works just like a randuins slowing all attack speeds good against attack damage carries.

I am aware of my masteries for i dont use them and not good with them but that was what i came up with but do not recommend using. The runes on the other hand are great for early game and stay into effect until the end or laning phase.