Malphite is usually Tank not Dps. i tried once this my build and it showed to be quite a massive killing machine.
Making this kind Malphite you farm lot of gold with passive cleave and wriggle, on fights you activate BS to make max damage and saving health( Cleave is good in mob groups and if there is enemy champpion next of them and you hit with wriggels passive you make 60% of that damage to your enemy).
Unstoppable force is good if you gank champpions, you get that way 400 magic damage to them imidiadly and they are stunned 1,5s, when they land use ground slam to make their attacks slow, while that activate Brutal Strikes to start save HP and deal damage, if some1 tries run away use seismic shard to slow he and you catch he easilly, there near use ground slam and activate again brutal strikes (if they arent dead allready).

This Build Fits fight against Casters,Tanks,Dps champpions, you just need use right skill order and they are gone, But Dont try alone take too many enemies with full health (especially if they have stun or silence).

Change Ninja Tabis to Mercury Boots if there is Stun Champpion on enemy team, it will gives you bigger change to survive and kick that ***,

And Wriggle is There becouse there is Cleave skill and if that Wriggle activates while some enemy is hitting creeps near of you, they will get around 400 dmg with that, so Powerfull Not at all. And there is Change even to make Wriggle&Crit same time so it will be more nice that you can even think :D

So Malphite Can be Quite a Dps Even Looking that hes Mostly used as tank in game.