This is how I play Rammus and am very sucessfull doing it. I love being the tank in the team becuase if played right many games, yes even ranked games rammus will finish with 0 DEATHS. I love this about him, he has the power to run with his Power Ball (PB), his AMAZING CC with his taunt, his slow from his PB and when you give him upgraded exausht its just crazy. I hope you give the build a try and are ready to be situational with items.

This is where the build gets interesting, becuase there is NEVER A TANK WHO KNOWS WHAT HE IS BUYING EXACTLY BEFORE THE GAME STARTS. If you know what your buying before you see there team then....well I will just hope you dont.

VS 5 AP CASTERS
Merc Treads-->Force Of Nature--> Banshees Veil--> Guardian Angle--> Quicksilver Sash.

A good Mix but there Caster is feed
Merc Treads-->Aegis of the Legion-->Force Of Nature--> Banshees Veil-->Randuins Omen--> Guardian Angle

There DPS is feed
Ninja Tabi/Merc Treads(It depends on the amount of CC they have)-->Aegis of the Legion-->Thornmail-->Banshee Veil-->Sunfire Cape-->Guardian Angle

Very Heavy DPS
Ninja Tabi--> Thornmail-->Omen-->Sunfire Cape-->
Guardian Angle--> Banshees Veil

A good Mix
Merc Treads--> Heart Of Gold--> Force Of Nature-->Thornmail-->Sunfire-->Banshees Veil-->Guardians Angle
(Sell the Heart of Gold or upgrade to the omen)

I go with the choices of Exhaust for extra CC and Teleport for those times when YOU JUST GOT TO SAVE THE TOWER. A great combo to wipe out a large wave of minions is to PB into the crowd then ult and it can clear a HUGE pack of them at one of your towers.