Hey this is my first build for any champion so i hope it will help you guys out.

The runes that i chose are runes that will give u some HP and armor in the early stages of the game. Especially if you are solo top or a jungler. Later on the Magic penetration rune comes into play with ur defensive curl ability and ur ulti. Which will help u own.

The masteries are standard defense masteries that helps in early game. It will reduce a lot of the damage in early game.

The items that i put are just for a general tank build. A must for rammus is thornmail because it goes well with his defensive curl ability. I also thing it is good to get it early even before u get boots because rammuse doesnt really need speed his got that power ball ability that gives him speed. Another must is the sunfire cape because it gives u passive damage out put and rammus is all about the passive damage. When i comes to Randuins Omen it can be replaced by Banshees veil if u are playing against a heavy AP team. You need the Warmogs for the HP. Just remember as a tank to build against ur opponents attack. So the more AP they have the more magic resistance u build nad so on.

The skill sequence is important. I think its best to max Defensive curl and taunt. Taunt can be used early game to drag the enemy close to the taunt for kills or to help or jungler gank. Also the defensive curl works well with taunt top force the enemy to attack u.

As a tank such as rammus u must initiate fights. But also protect ur dps and ap teammates by using taunt whenever possible to get the attack directed at them focused on u. Because remember rammus is a passive damage dealer so if they attack u u will win. With all the passive damage u deal.