Hello and welcome to the guide. It's a bit "wall of text" at the moment, I will give it an overhaul soon.

There are many Rammus guides around, many of them cover tactics and strategies in great depth and detail (Bguggs, I'm looking at you). This guide won't go into any of that stuff as it has been throughly covered already by much better players than myself. This guide is for folks who know what they are doing in The Jungle and understand the mechanics of Rammus and fancy some new ideas.

I've spent almost all of my time in league playing Rammus. I've read most of the guides on MOBAFIRE and incoporated something I liked from each into my playstyle and build. A good example is the "current meta" Rammus build. I don't have the skill to pull that off unless I can get some really lucky ganks, however this build keeps the damage output nice and high whilst remaining tanky.

For me, runes and masteries are all about boosting your early game. To combat repeated nerfs to Rammus, these masteries and runes look at boosting your damage output in the beginning of the game, as well as helping out a bit later.

The idea behind this guide is to maxmise Rammus' ganking potential. Since you have the best, longest and most "omg that's so OP" cc in the game, your ganks can be improved by arriving with more HP and doing more damage.

When I started writing this guide I was going to go into the maths behind many of my decisions. Sadly, this guide would be epically long and probably not make much sense. Instead I'll provide a brief outline of my thinking behind the scenes:

Greater Quintessence of Vigor is great early game due to all the time between camps/ganks. Combined with a Regrowth Pendant and the masteries, this gives LOTS of Health Regen.

When it comes to marks, there's a great range to take. I've chosen a mix of Greater Mark of Desolation to hit harder and Greater Mark of Attack Speed to get through the jungle a bit quicker. I've limited the total armour pen. in this build so that you dont have an excess in the early game.

Rammus has a natural steroid move, Defensive Ball Curl. This increases his resists by 60 at level 2, a huge damage reduction skill. Not only does this skill increase resists, it also returns damage that scales with your armour every time you get hit. As such, early game items are based around getting HP and HP/mana regens.

Initial Buy: Regrowth Pendant and Health Potion

HP/5 should not be laughed at. As long as you can survive the bursts (whether that be whilst ganking or from doing a buff, the regen will get you back in business nice and quickly. Hopefully you should have your Defensive Ball Curl on during the bursty bits of a game (that's where the skillcap on Rammus comes from) to mitigate most of the damage. Starting with Regrowth Pendant and Health Potion is the most effecient starting set, getting you onto a Philosopher's Stone straight away.

Stage 1: Philosopher's Stone and Ninja Tabi. Make sure you get some Sight Ward.

This gets you level 2 boots (hopefully whilst all the carries are on level 1 still), nice health/mana regen when wandering through the jungle, some damage reduction against your main damage source and Sight Ward. Sight Ward win matches, steal buffs, set up kills. Buy them.

Stage 2: Hexdrinker, Kindlegem.

Now you start to really make an impact on the game. A nice health boost, CDR, some AD to hurt in ganks and the best bit is the shield. Rammus is normally built with a bit less MR than other tanks, relying on the player skill to hit Defensive Ball Curl at that crucial moment ( Karthus ult anyone?). The shield from Hexdrinker starts to really pay off in this stage of the game and often makes me laugh when I survive what should have been certain death.

Stage 3: Finish off your Shurelya's Battlesong

Yes I know all the other guides say sell your philosopher's stone after 30 mins. They are wrong. Rammus is severely lacking in HP. Shureylas Reverie gives a lovely HP boost, along with plenty of regen to make up for the lack of lifesteal found on junglers who use Wriggle's Lantern. To top it off it has an awesome active that makes you Powerball like a bullet. None shall escape.

Stage 4: Warmog's Armor, Atma's Impaler, Wit's End & Maw of Malmortius

Build the Warmog's Armor next as fast as possible. You'll have to rely on Defensive Ball Curl to help you with resists for the moment. Often I take level 3 Defensive Ball Curl the next level after I've built Shurelya's Battlesong. Then it's a case of whos doing the most damage, build your next item accordingly. Taking AD? Build an Atma's Impaler, increasing your damage output AND armour. Taking AP? Build a Wit's End / upgrade your Hexdrinker, increasing your damage output AND magic resist. Remember to keep farming that Warmog's Armor on lots of little creeps as often as possible.

Comments on final build

Shurelya's Battlesong, Ninja Tabi, Maw of Malmortius, Warmog's Armor, Atma's Impaler, Wit's End

Nice and tanky with 3500 HP, 170 AR, 140 MR

Great damage output from Atmogs, Wit's End, Maw of Malmortius

Great passives from Shurelya's Battlesong, Maw of Malmortius

Not the tankiest Rammus you can build but you can do "tonnes of damage" and still tank. You'll need to take care activating Defensive Ball Curl though. You get more damage as you get less HP from Maw of Malmortius. You also get a nice shield at 30% HP. You need to balance these two benefits with when you activate Defensive Ball Curl which will shut down most of their damage. Is everything going great but your team is lacking just a bit of damage? Build a Leviathan to quickly gain HP whilst Working your way up to Atma's Impaler/ Wit's End/ Maw of Malmortius. Lol.

Build 2: Things go badly

You've played for 15 minutes, bought your Ninja Tabi, Shurelya's Battlesong and Hexdrinker but still you cant carry your team. Ganks are failing and your stats are 0 5 3.

In the immortal words of Douglas Adamas: "Don't Panic"

What I like about the core build is that if it isnt working, you can adapt. Grab a Giant's Belt asap. Get a Chain Vest and a Negatron Cloak in whichever order is needed to reduce your main damage source. If needed you can sell your Ninja Tabi and Hexdrinker and get exactly enough money back to buy Mercury's Treads.

Generally if things are bad and the damage is a balance of AD/AP I would try and end up with:

Shurelya's Battlesong, Ninja Tabi, Maw of Malmortius, Warmog's Armor, (same as before) Randuin's Omen, Force of Nature

This significantly improves your tankiness, keeps your Hexdrinker shield and Ninja Tabi damage reduction. Personally I think Shurelya's Battlesongis an essential item on Rammus.

This build gives you:

3900 HP, 204 AR, 166 MR
Still have 222 AD
Get a new and utterly awesome passive from Randuin's Omen

Build 3: CC heavy team

Shurelya's Battlesong, Mercury's Treads, Randuin's Omen, Guardian Angel, Warmog's Armor, Force of Nature
Full tank masteries: 9 21 0
Runes: Stay the same, these runes are for Jungle Rammus

TL;DR

If like me you've looked at several guides and taken away what you like most from them rather than following them blindly, please take away these points (TL;DR):

Tabi are good and HexDrinker compliments them well, providing a powerful early game.

Shurelya's Battlesong is awesome (HP, HPR, MPR, CDR, amazing active)

BUY WARDS

Go read Bgugg's guide for how to play Rammus