Mundo Viable As Support Or Not?

Hey GD-- err I mean Boards. My first thread since the change.

My question is: "Is Mundo support viable or not? If not why? If yes how to build him, what runes,masteries and against who to play him and not play him?

I played 2 normal games as Mundo support against Leona and Sona as supports and won both times. Got my ADC fed and just wrecked bot lane, then continued to wreck entire game. I build him in this order: Relic Shield-2 pots- yellow trinket ---> Sightstone - Boots - Oracle Sweeper---> Giant spell Or Chain West---> Sunfire Cape - Face of The Mountain - Upgrade boots depending on enemy team comp --> If heavy Ap enemy team --->Spirit Visage --- If Heavy AD comp I neglect MR and go for more HP and Armor or Frozen Mallet.

Now, I'm just a silver scrub so I don't know if this is the right build or not. But I've found it quite strong. Any advice from Higher Elo Support mains or Mundo Mains? What do you think? Slurp

P.S. Idk where to put this thread. xD