Lets keep this simple.. In Dominion you need to get places. You need movement speed. This is how you will build Rammus. Please give this a try and remember to build thornmail before Phantom Dancer is complete.

Pro
-Help take over places quickly.
-Supports team whenever needed.
-Can help grab the top early in game.
-Wont have to worry much about AD champs especially when you have your shield up.
-Other teams melee will be afraid to attack you because your a suicide machine.


Cons
-AP does alot of damage.
-If you don't taunt them first the melee may have a chance at winning. [Ex: Nocturn's fear]
-Not much health.

Basicly.. As soon as the game starts you hit ghost and then you do powerball the moment you exit the base onto the field. Then you make your way throw the move speed buff all the way up and then finaly flash over the wall and take it over. You will almost 99% of the time.. get interupted by the enemy before your team comes to help. Do not continue taking over. Just taunt and use your shield.. tank them off until team comes. Finally as your team comes and chases them off instead of taking over [99% of the time], finish up taking over and either defend or recall for the next item.

+ Remember to get a Zeal and the IMMEDIATE next item is thornmail. NO FORCE OF NATURE. Thornmail.. this build should not be used if playing against full AP teams anyways.. but it should work regardless.

Finally.. When you begin fighting. Hit your shield and taunt + ultimate. If you have the phantom dancers and thornmail its an auto kill most of the time. You may want to invest on a starks fervor aswell to give you team a little something and to get some life back while you make kills.

Have fun abusing in Dominion.