Rammus is a fast tank that can run in and out of battle and in dominion he is the best at capturing points at first and mid game unbeatable in defense and taking over points and chasing down your prey.

I chose Armor pen reds and quints for Rammus because when you start fight when you have boughten black clever and Thornmail you will start craving what little armor they have not many people think to build that in dominion you will cut through what little base armor they have.
Armor yellows of course it will give u some extra damage and durability.Magic resist per lvl glyphs for those nasty ap champions you will fight.

First I begin with boots of mobility and a cloth armor gives You the speed that allows You to dart in and our of battle and annoy people capping points.Next I start saving for my thornmail then to black clever . Force of nature next for the movement speed and magic resist plus it gives You ok health regeneration. Then randuin omen for the slow and armor and it has good health regen. And last agegis for both magic and armor resist and armor and gives a nice aura for your team. And by now your armor should be massive and pretty decent magic resist making you a wrecking ball of hurt and bad news for your enemy

I upgrade his power ball and defensive curl first they give him crazy mobility to shoot across the map and the defensive curl gives him a boost in armor and magic resist and give enemies magic damage back.knowing when to taunt your enemies to draw away focus from your teammate that is dying and then activate defensive curl and start attacking and using your ultimate tremors not really a powerful ability but its damage to your enemy. The thornmail will cause them to receive 30 percent of their damage back to them in magic. And may i also add your taunt reduces their armor and your black cleaver also will do the same making them die quickly especially if their master yi.I use power ball to dart around the map to annoy enemies by capping unguarded towers and make sure you run through the speed shrines and watch your movement speed sky rocket. Also to stop enemies chasing your teammates then taunt then defensive curl its a great combo just try it out. plus his passive is amazing converting 25% of your armor into attack damage

Ghost and garrison . these are a must to have it gives him more speed and reduces damage their turrets give so you can dive and get kills

why I went 1-21-8
i went that one in offense for the improved ghost making You faster . 21 in defense for the sustainability and give him more of the tankness that is Rammus. And last 9 in utility for the movement and improved recall is what i wanted most.

pros
great at tanking and surviving and running in and out
great late game
good at taunting and saving teammates

cons
your a bit squishy at first
very item dependent
doesnt have a joke :(

Give it a try I have fun when I play Rammus like this people don't expect you to kill them don't down vote I like feed back let me know your suggestions