Rammus is a tank. Your goal is to tank damage and CC enemies as much as you can. With that skilling order you only have slow untill lvl 13 and not to mention that the slow comes from Powerball which should be maxed last. You - taunt and tank them. Not Powerball in and stand there with your deffensive ball curl. Now, next there are items. You can't use same item build all the time. Here, you only stack armor. If you face a team made out of something like Mordekaiser, LeBlanc, Lux, Ryze, Master Yi you are insta dead. Most teams are hybrids, (some ap some ad and a tank) that's how you should build a tank too. As a armor/magic ressist hybrid. This build works only when you face a fully ad team, which is really rare. If you want to make a good tank guide you should give a description of most viable tank items for Rammus and tell them when to buy them. You can't play tank with same item build all the time. There are too much magic damage dealers in this game. So you should post builds on what to buy when you face a magic damage team, AD team and hybrid team.
Will see if you improve your guide and i will rate it only then.

The idea of Rammus is that you can taunt. Taunting keeps your enemies close to you, which is awesome for you Tremors and Sunfire Cape, and it also deals damage in combination with your defensive ball curl and Thornmail. So for not taking the taunt at all untill lvl 13, not taking a third point in your ultimate, and no description, i am going to -1 you.