This is a build of Rammus that covers all what he needs Health to be a tank, magic resistance, armor for his abilities and a little of cooldown reduction what makes him hard to kill and a hybrid tank

I pick up in one runes of magic resistance (marks), armor (seals) and mana regen per 5 sec glyphs and of course health Quintessences what makes him a hard killer.

In the second build i pick magic resist (marks) as in the first health regeneration per 5 sec (seals)and a few of armor with armor glyphs that makes a great defense against magic.

The masteries in the first are 0-21-9 focusing the defense part as all tanks and giving him health regeneration by his maximum mana and also giving his ghost spell more speed and time of use.

In the second are not much different it's a 1-21-8 which gives a better exhaust spell and focuses on the less time dead and mana regeneration.

I chose for the first build a maximum armor and health Rammus focusing on dps champions or critical champions as Tryndamere or Xin; first of all we begun with doran's shield as any tank does next we have boots of speed for more speed that then are converted to ninja tabi for a little more armor after that we buy giant's belt for more health converted to sunfire next Thormail this is the most important item for Rammus because with his second ability makes him op then guardian angel continuing by randuin's omen and final by frozen heart

For the second build we have the same beggining with doran's shield and ninja tabi but we focus more on the magic resistance part and cooldown reduction few than the first one but also some and health with banshee's veil, Spiit visage, guardian angel and Force of natuer and also good for Rammus but as last item Thormail

In both cases the skill order is the same beggining with powerball and leaving it until level 14 meanwhile u have mastered first your taunt followeb by your defensive ball curl and your final tremor leveled up in his time lvl 6-11-18 respectively

The summoner spells i chose were Exhaust and ghost. Exhaust is useful in hard situation like ganks or scapes also as a chaser spells combined with your taunt u can do a lot of damage, Ghost is as all Spells the one you use for scaping with less life or chasing if the enemy is far away

The best way to creep is using your defensive ball curl as a way to increase your armor and your attack damage as well when there are some minion you can use your powerball to damage all surrounding minins and having an advantage for last hitting them and farm.

Pros:

High armor
High damage
High health and magic resistance

Cons:

you are sometimes vulnerable to ganks if you dont have your final available
Summoners can combine magic damage and phisical damage so it will be good for you to buy some of magic resistance or armor in each build