I actually have just started playing malphite again but I've been trying different builds because he does such low damage after 40min but also a build that will deal with his mana problems.
The new build I'm trying is:
Doran's Ring - adds to your Q harass and should provide enough mp5 with glyphs
RoA (boots and mana crystal on first back) - this combined with being smart with your spamming should solve your mana issues
Standard tank items (Frozen Heart, Sunfire, FoN)
I find banshees bubble isnt really necessary on tanks and the money can be better spend on mitigation. I like this item much better on squishies where the bubble can save your life. Plus if you are building RoA you are still able to get the added health and mana but get AP which is more useful.
I still need to test it out a little bit more but so far this solves your mana issues early while also allowing you to deal significantly more damage than many will suspect from a malphite at that level.
I have tried the chalice solution and it does solve mana issues but there are a few reason I dont really think it is optimal
+ it delays you being able to build armor which then becomes damage due to your E move
+it delays building RoA which will give you early tankyness and allow more damage from the AP (Ult is on a 1:1 ratio I believe)
+while it is a cheap item this can be deceiving. Dont think of it as only costing ~1200 gold, think of it as setting you back 5 minutes from a more important core item to your build
+becomes a wasted slot laterIMO NEVER take clarity......exhaust is too important on your tank to waste the slot
Any feedback on how RoA works for you guys would be helpful.
FYI: My tank runes are Q: Movement Speed, M: Magic Pen, S: Flat Armor, G: mp5/lvl
EDIT: 9/21/0 masteries