I just recently purchased Malphite and am learning how to play him. I almost never play solo; I'm usually on Vent with at least one other player, most of the time two or three, sometimes a full team.
I bought Malphite for a few reasons: He is an amazing Jungler from level 1; he has great survivability, which makes him much less likely to get ganked in many scenarios; he is a great ambusher.
Since his armor nerf, I've been taking the Defensive tree (I'm only level 14, so no 9/21/x for me or what have you) to make up for his early game. I've been following the old Jungling guide:
1x Cloth Armor
5x Healing Potion
Summoner skills: Heal, Smite. I seem to need Smite to make up the damage at low levels to kill the Golem and the Lizard, and I seem to need Heal to survive, even with the health potions. I tend to hit the Golem first and work my way around to the Lizard last, then go buy, then hit the other jungle.
First, I buy Heart of Gold as per the Jungling guide, then start working on Warmogg's Armor. But I'm not sure how much this helps. Should I, as Malphite, be stacking health (great synergy with his passive)? This produces a tank, yes- but Malphite seems to not be terribly resilient in the late game, even with 4k health. It goes without saying that most champions die when focused but they tear Malphite a new one, for him being an "in the thick of it" character.
By the end of the game, I tend to have worked on. if not finished:
Heart of Gold
Mercury Treads (level 3 boots if enemy team doesn't have a lot of CC)
I'm not really sure where to go after here. Stacking health seems to be great for survival but not for damage output. Even stacking armor is too expensive to give appreciable results. Cooldown reduction is great but it makes me totally reliant on the Golem buff, which can be very competitive to get later in the game. Is the Chalice worth getting on Malphite?
Any suggestions would be greatly appreciated, including gameplay suggestions (for example, my ultimate is great for Initiating but Malphite doesn't seem to have enough "put down power." I'd take Ignite or Exhaust but I just can't afford to lose Smite and Heal right now.)