OK!!! you decided to finally play Rammus. However, there are many builds that can fit the lil guy. So upon realizing this you want the best build that will get you somewhere and actually get the advantage. I'm not gonna go into full detail because the build itself does the talking just read this guide and trust me you will see the results for yourself. and please don't knock till you try it.

When i tested this build i ran through so many runes and a lot of ip. i went with 18 armor pen to start off with due to the fact that rammus is fast however he does not do jack **** for damage and a lot of people will always make it up with either resist or armor or just health runes. which works BUT if you just give him that extra lil help it will go a long way. Now with the yellow and blue i went with cool down reduction. and everyone who i told this flat out asked me why. Heres that answer for you. when you get tremors the cool down is pathetic. with the cool down reduction it cuts it nearly if not just a lil more than half. Thus making that lil fella the biggest pain. Now the quints i went with health and mana regen and the 3rd armor pen. (can never have enough armor pen ^_^).

summoner spells ghost and ignite. why? speed and that lil fire to watch them burn flat out....
(maybe a pyro not sure) mastries you want mostly offense now i know this sounds stupid however, like i said you will understand why when you try it out. (i know poor guideline but i just really cannot explain it.)

Ok now your thinking this guy is just a moron and making **** up.......NOPE!
start off with boots (obviously eh...i thought so also) and 2 health pots and a mana pot.
you always want your 1st skill power ball. you want to give your partner the space he/she needs along with put the other team away from the minions. its always the best way to go including if your going against melee or other tanks. get your ninja tabi done then move to thorn mail. with those 2 items will give you enough time to work on warmogs armor. at this time you should allready have your basics taunt and defence curl. (be sure to get taunt 2 times before your defense curl(the longer you taunt the better). now your asking yourself why 3 warmogs and no ap resist. well its rather simple by the time you get 3 warmogs up you will literally have 5k health if not more. (more than enough to eat almost anything....by the way hey karthus u can't kill me when i have that much health and when that ulti of yours pops defense curl and didn't do ****). by this time if your team is decent you should have around 13 to 15 kills (like i said before it gets better.) now lastly atmas impailer. Now here is where it gets nasty. by the time you get this lovely lil item you should have 7k health. with the damage you do with thorn mail plus atmas you do 2% of YOUR max health. (ok it dosen't sound like much however, if you actually sit down and do the math well it racks up quickly. I have seen so many rammus start with dorians shield and i laugh every time due to the fact yea you got extra defense...big whoop thats where that armor pen comes into play. this build will work for you in the long haul.

I understand that many people bash other builds and such and hey opinions are just opinions.
like i said before if you like it you like it if you don't then well pretty much you don't.
however, at least give it a shot i've used this build so many times and stomped so hard with it.
last time i played rammus with this build i went 26/2/20. I play for the fun of the game. If you just baught rammus or have him and just don't play him try this build. It will not let you down because if it did to me I would not have posted it. Oh and by the way, This build just brings the new meaning of fun and distruction at the same time... Happy hunting and go Power ball into someone and ruin there day.