Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
-- Forgot to login before posting this build previously, so I am re-posting. Plus I would like the ability to edit. --
This build is to enable you to not waste gold on pots if you chose to jungle, and not having to change item builds but only rotation of purchase to counter specific damage types. I'm going to keep this as brief as I can because if you are like me, you hate reading excessive guides that probably aren't that great to begin with *eep*.
View "Skill Sequence" section to build if you are to lane rather than jungle.
Pros / Cons
Easy to use, flexible, never have to change your item selection.
By being limited to 3200~ health you may be subject to attention, be ready to run in - do your role - and get out.
I find that Flat Dodge yellow, HP Quints, and Flat Magic Pen red are all necessary to efficiently jungle with this build. If you intend on using this build to jungle I would suggest getting mp5/level blues. If you are not going to jungle mana should not be needed as much and you can pick whatever you like for blue, and even Quints if you like.
I chose these for masteries because I like the durability you get from them, the bonus xp gain which can make the game while in the jungle, and for the health/mana regen option. If you are not jungline then you may take the point out of Plentiful Bounty and place it within another.
If you caught on that I have 7 items listed including the Philosopher's Stone, then good for you! Whenever you need your 6th item you will sell the Philosopher's Stone. If you are doing well you can build Randuin's Omen early, if not I would leave it as Heart Of Gold until the end of the build; this ensures steady gold flow. Depending on what you are going against for damage dealers you can build Banshees before Sunfire Cape, or Sunfire Cape before Banshee's Veil; as well you can decide if you would rather have dodge boots, or not. If you are not jungling the health pot is typically not needed. I prefer prioritizing Guardian Angel over Force Of Nature due to the fact it enables you to be a crazy tank and make turret dives possible, that very much could change the game to your favor.
I chose what I did based on jungling. If I were to be laning I would always prioritize taunt, but while having powerball as my level 1 skill. For Example: Q E E W E R ... only picking W when you cannot pick E, always picking your ultimate when you can, and always picking rank 2+ powerball for last. The only reason I pick W first in the jungle is because it helps drastically with burning down minions.
-- Despite not having a huge amount of health you will find you are quite durable. --
Flash is pretty much a must. You can use it to flash then powerball away to safety, to surprise enemies, or flash ahead to get in range of that taunt and or powerball. Your second spell is flexible but if you are jungling you will definitely need Smite. Teleport is nice if you want to start a powerball then teleport in, always a classic. Or ghost if you feel the need for speed, or Clense if you don't like getting bossed around. Regardless all of the common spell bonuses can be upgraded with that extra mastery point I left you!
Start at golem(blue) - use your hp pot immediately, you will need the blue bonus. Next clear the wolves, and then the wraiths. At this point depending on how lucky your dodges were, you can proceed to the golem set of two or head back to base to heal. After you clear the wraiths you will have enough gold for your first item upgrade. Next obviously clear lizard(red), and you decide what to do next. Jungling seems to be rough after you run the first sequence, I suggest you ask your team mate if you can jump in and out of the solo lane on occasion to get some mana back, otherwise you will surely oom when you need it most.
The reason I max taunt as quickly as possible is because of how effective it is with ganks. Obviously your team has to not suck, but regardless even with a bad start you can pull the game around. Don't be afraid to use your ultimate to farm creeps or get the golem, it has a short cooldown and will likely be back up before the next team fight, just use judgement. Also don't be greedy with red, granted after you hit 6 you can probably solo most enemies but let someone that needs it get it instead. DON'T FORGET TO USE YOUR RANDUIN'S OMEN!!!
This reading isn't mandatory, and is only here if you need help playing Rammus.
Spiked Shell(Passive) - Converts 25% of your armor into physical damage.
Powerball - After casting you gradually increase in speed, you gain the most speed near the end of the cast. This ability can be cancelled any time after cast. Any unit collision while using Powerball will deal described damage(and in a small aoe vicinity), and cancel the Powerball animation+speed bonus; also be wary of walls, they tend to sometimes cancel this effect as well. Clicking a unit directly will cause Rammus to get within auto attack range and not collide; rather you must click past the desired target. While jungling it is easier to position yourself against a wall to push the creep into the open when you collide. This ability cannot be used while Defensive Ball Curl is active.
Defensive Ball Curl - Grants you bonus armor and magic resistance, as well returns 10% of your armor as damage when struck. Great ability to use while turret diving, while taunting a fast hitting champion, or if you know you are going to get focused. This ability can be cancelled while active.
Puncturing Taunt - Reduces enemies armor for the duration, and forces the enemy into attacking you. The range isn't quite as good as Shen's but due to the fact you don't have to reach to cast this ability, it's great for pulling enemies into your team or your turret.
Tremors - Deals damage per second in a small AOE around Rammus. This ability is amazing if you need to clear a large creep wave fast. It also deals damages to structures, making it ideal to destroy turrets and hold tower fire if you need to.
Ideally you want to wait until your Powerball is near the end of its duration before popping out of bushes, as this gives you the biggest speed bonus making it harder for enemies to run. If you happen to be at the top of the map while your teammates are at the bottom and they are in need of help ... instantly use Powerball to cruise to the bottom, it should be off cooldown by the time you get there.
The armor reduction on the taunt helps but shouldn't be your reason for using it. Taunting can be extremely effective in saving your team and saving yourself. If you need to peel an enemy off your team while escaping yourself try to land a taunt and run off in a direction enough to where your teammate can get away. If you are in trouble yourself at the end of the taunt blow your flash and or Powerball away. Remember that ranged will stay at max range before chasing you in a taunt.
Creep wall...*FLASH* SURPRISE JUST KIDDING! Flash is great for leaping out of the woods and landing a Powerball, or even teleporting through a creep wave to get to an enemy.
Timing Ability Use:
If you are opening up with Powerball and have the aid of teammates, it is likely your teammates will try to land a stun or snare after you hit the enemy with your Powerball. Make an assessment if this is the case, and if it is wait a couple seconds before casting your taunt. This will leave you closer to using Powerball again when your taunt runs out. If the enemy has a lot of channeled abilities try to save Powerball for the use of interrupting them; being that Powerball deals damage a small vicinity of which you made contact with you can interrupt multiple targets at once.
Every champion seems to move and interact a little differently. Don't be afraid to ask your teammates for help, you might look like a noob but I bet they'd rather help you than lose :)