You know him as a Tank. You know him as a Snare. You know him as a Jungler. But if you've been paying attention, you know that Amumu is best defined as something else: an initiator.

Amumu's job is to have a giant pair of balls. He gets in--by walking, flashing, ghosting, BT'ing, or however you will--right in to the heart of the enemy team, and then poops damage and CC. Amumu can do this for two reasons: one, he is a tank, and he can take the start-of-fight burst damage it takes to get to that position, and two: his damage all comes out as AoE around him, making that position he gets to absolutely key.

Since he's so solid, and since he can still get decent damage output, Amumu dives in, and does some serious starting damage to everybody else while his teammates rush in. As they're about to leave, Amumu gracefully times his Ultimate, Curse of the Sad Mummy (henceforth just R, for the button that calls it), to grab any enemies who might escape.

And so, you ask, what is Amumu's weakness? He sounds like a tank with viable damage output, decent CC, and jungling superpowers. Amumu's weakness is a very odd one--oddball that this little kid is. Amumu cannot focus damage. Not on one enemy, nor at one time. His damage comes out slowly but surely, as long as he's still there. So you have to make it count.

This guide will focus how to make Amumu's damaage count, how to make his snares count, and how to time Ulti right, and space it right, and time your whole teamfight so you only ever leave right before you would have died. We'll go through some of the standard justification for runes and masteries before we get into fun stuff like Item Builds, Team Roles, Team Fight Strategies, and Farming Strategies.

The runes are simple:

MPen Marks, because they're the only primary Marks that are useful on Amumu. Amumu gets MPen and MPen-like effects from here and there, and more of it doesn't hurt. MPen actually helps make him more of an Anti-Tank--more on this later, maybe.

Seals of Clarity (mana regen per level). Why? Well, running out of mana always stinks. And with Force of Nature, your health regen will be fine late. So keep up your mana the whole way through with little things like seals, and have your health regen come from your first item, and then later from Force of Nature.

MR/level Glyphs, because MR is hard to find (relative to armor), and this is a very effective way to get some.

Quints of Fortitude (Flat Health) give you solid survivability early on (which is another thing Amumu needs) while not being useless by the end.

Masteries are pretty simple too:

On the defensive tree, go 21: give Amumu every defensive stat you can, other than dodge (dodge on Amumu is a point of contention, and while I don't mind it, the other defensive masteries treat Amumu better--more on Dodge in the skills section). This will, if you followed it the way I did, bring you up to 18. Then, put 2 points into the "defensive" mastery that inexplicably gives you AP and AS (meh, neither really hurt), so you can plop the 21st point where it belongs. Then, just pick whichever first 9 Utility points you like best.

Amumu's passive, Cursed Touch, reduces the enemy's MR by 15/25/35 for 5 seconds. This is less thrilling than, say, Fiddlesticks' passive, and is not always worth sticking your neck out for. But you might underestimate the amount of extra damage it lets you do. Do try to get attacks in on your enemies, and keep them gimped--not only for your damage output, but for your magical teammates'.

Tantrum should usually be your first skill. Bandage Toss (BT) is better for first blood, but leaves you unable to farm or effectively hurt minions until level 2, and its high Cooldown means that your one or two BT's will be all you can do until you get Tantrum, and that's annoying.

At level two, put one point in Bandage Toss. Bandage Toss stuns an enemy, pulls you toward him, and does a decent bit of damage. This will be the last point you put there in a long time. You may be asking why you don't level BT earlier--it deals more damage, and its CD decrease means you stun more often. Alas, the problem is the increase in Mana cost. Wait until you're a higher level, and you can spam BT, before you let its mana cost go up.

Maximize Tantrum first. Tantrum's passive damage reduction is nice, and allows you to blow through minions. It's nice for jungling, too. What's nicer, though, is that while the CD goes down and the damage goes up, the mana cost stays the same. By level 9, you will be hitting E every couple of seconds. This is good.

Also notice that Tantrum cools down faster the more you're getting hit. This helps in taking out huge clumps of minions, and such. It's also why people argue about Dodge on Amumu. I think that dodge is a relatively cheap way to make damage disappear, and if you want some, go for it; but if you don't really want it, feel free to stick with armor and MR. Finally, it generally makes the cooldown on Tantrum making its damage output close to continuous.

Despair, your W, gets its first point at level 4. Like BT the mana cost makes it less useful at lower levels. But Despair becomes useful much faster than BT does. It allows you to throw in some percent-based (and thus, again, anti-tank) area damage to the area around you. Note that Despair's damage is not capped against jungle monsters, and that it is thus very useful against, say, Dragon or Golem. Also, note that with Despair's continuous nature, Amumu's main two damage moves are non-burst moves. Amumu will deal more and more damage to everything around him the longer he lives. This is good, because he's a tank. You have to make this convenience work for you. Always be in the middle of your enemies, constantly pooping out damage, and stay there until you're about to die, or until the enemy team has sufficiently dispersed from around you.

So, how do you keep them close enough to keep damaging them? How do you set them up so your team can knock them down? And why is Amumu known for being an R-Button Champion?

Amumu's Ultimate, Curse of the Sad Mummy, is just tits. Amumu snares everybody within a nice big range around him, and does a good bit of damage to each of these enemies. Finessing the timing and spacing of this move is just a matter of experience; play with this move all you can. And notice, this is what makes Amumu your great initiator.

Once they see you show up, your enemies will start to disperse--run away from each other, so you can't damage them all. Don't worry about this. Around teamfight time, you can afford to use Despair and Tantrum both even if you're only hitting one enemy (although you should try to get two or three), and, as far as Ulti goes, 3 is plenty, and 2 might get the job done--these 2 might mean 2 kills for your team at the press of a button. If you have the CD low enough, consider using R to secure just one kill, or even to get away from a sticky situation (the rooting gives you a half-decent chance to get away).

Also, CotSM comes with a really cool animation. Enjoy it.

The short version:

Build moneymakers. Pick your boots: Speed, Dodge, or, most likely, Merc's Treads. Build Sunfire. Build FoN. Win.

The more in-depth version:

I like to start with Regrowth Pendant and a potion (either health or mana, depending on how confident I am in my ability to survive). The Regrowth Pendant is going to turn into a Philosopher's Stone, which will make you money until you're ready to sell it for your final build.

Next, buy either Boots (I recommend Merc Treads, but Boots of Speed or Ninja Tabi or even the new CDR boots could work) or your Heart of Gold, and then the other. Heart of Gold gives you some health and armor that's roughly worth the price, and helps you make a legitimate amount of money. It's important to the farming--explained below. Move speed is important on Amumu, for positioning, but he'll get some from Force of Nature.

Then, we get our way into your big ticket items: Sunfire Cape and Force of Nature.

Sunfire Cape provides some good armor, a decent health boost, and a constant 40 magic damage per second. Remember that Amumu often gets non-tank enemies below 0 MR, and that this does indeed cause that damage to increase beyond 40. The best part of this damage is the way it comes out of you--that is, the same way all the rest of your damage comes out. Between Sunfire, Despair, and Tantrum, it becomes safe to describe the bulk of Amumu's damage in terms of the damage being pooped out in an area around him, constantly.

Force of Nature provides the highest Magic Resistance of any item in the game, as well as an obscene amount of Health Regeneration--which will keep you out of base until you need to make a purchase. Finally, Force of Nature gives you a 7% speed boost, which more than makes up for the difference between Boots of Speed and Mercury's Treads. Nonetheless, keep in mind that move speed is rather important on Amumu, not only for chasing and running away, but for positioning him properly--which is the only way for him to poop damage.

Now, for items that are nice, but not necessary. Finish off your build with three of these. Don't forget the obvious: balance your Armor and MR based on the enemy team, don't try to pair Rylai's with Randiuns, don't bother with too much CDR (Elixir of Brilliance and Golem Buff put you at (roughly) max CDR. You don't really need much more).

Guardian Angel. It gives you decent armor and MR, and, if you die, it brings you back to life when you die. Simple enough. You might want to go for some of the flashier effects--slowing, auras, ap--but coming back to life, especially on this Amumu build, can be very nice. For one, whenever you die with GA, your enemies have to crowd around your corpse to try to stop you from getting away. This opens them up to take a whole lot of damage as you go down in a blaze of glory. Secondly, it adds a constant amount of health. This is more valuable on a high Armor/MR low health build like this one: each point of health counts for more now (hey--as if we needed more reasons to get Force of Nature!). It also works nicely with Force of Nature, in that the longer you survive with lower-than-full health, the longer Force of Nature can do its dirty work. Again, though, remember: it is a pretty straightforward item, and, for most of the time you're playing, it won't offer you anything other than decent Armor/MR.

Abyssal Scepter grants you MR, AP, and an MPen-like aura. At first glance, you only really want one of these things on a tank. The AP bonus gives you 35 more damage with each hit of Tantrum, and Despair deals .007 * enemy health more damage every second, which isn't bad, but you could get more AP if that's what you were after. The 20 MPen is better than you might think here. It's a small number, but it's an aura your friends can partake in. What's more... It's an offensive aura! Remember your W, E and R? Remember Sunfire Cape? Remember how Amumu works? Most of your damage is magic damage in that exact range! Abyssal scepter could increase your total damage output by about 20%. How's that for aweseomsauce?

Now: get either Randuin's Omen or Rylai's Crystal Scepter. They both give health--Rylai's a little more. Omen gives you 80 armor, though, which is better than Rylai's 80 AP. Omen gives you a little more Health Regen, as though you needed it. The main difference, I find, is their slows. Randuin's passive is chance-based, and, much to your dismay, pushes your tank right up to the point where it's no longer worth attacking him, at all--just a touch past where you want to be, unless you have a taunt. Randuin's active works, but not as effectively as Rylai's, which is constantly affecting everything around you. Make your pick based on the tide of the battle, and the rest of your build. It is totally unnecessary to get both slows.

Others (more situational):
Frozen Heart: Get this if you can't dominate golems, or if you need more armor.
Warmog's Armor: Raw health. I'm not a huge fan, but it's there if you want it.
Zhonya's Hourglass: AP if you are in the mood for it, armor, and an interesting active effect.
Lich Bane: Some MR, extra speed, and a decent chunk of extra damaage--especially on a high-AP build.
Banshee's Veil: MR, Health, Mana, and an effect useful for one-hit casters, like Karthus. Would recommend this as your only MR item against a team that has only 1 caster.
Leviathan and Mejai's Soulstealer: What to buy if you're killing everything and never dying.
Thornmail: Obviously, something to use in a team with 4-5 AD champs. Won't see much play in legitimate games.

Jungling/Farming, How Amumu Can Fit Into Your Team, a Pro/Con recap, and some sort of conclusion. Enjoy it! Please comment, even though it's not all done.