Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Alright so, basically what we have here is an anti-death build, now the player needs to remember, Rammus' passive increases his attack per % of armor... so technically while you stack armor, you also stack damage.
This build is obviously an anti physical damage build, so obviously if your opposing team largly consists of magic users, make sure to buy items such as Banshees Veil, to negate magical spells, and Force of Nature, to increase Magic resistance.
The summoner abilites are to use after initating, and staying in a fight until your life is low, to get away saftely, and to avoid being a dreaded feeder.
Now... you Rammus newbies...POWERBALL is NOT! a priority, only get one level of this as to stun and also catch up to enemies NOT FOR DAMAGE. Puncturing Taunt, and Defensive Ball Curl are the meat of the build for Rammus.
In conclusion, this build is obviously subject to change, i mean, you might be fighting magic, or you might be fighting hard core melee fighters, so in that sense it is versitile. You must adapt to the team you are fighting.