Explanation

This is my first build, and it will be a jungle Amumu, which is my main champion. It will take you 3-4 games to learn how to jungle well, where the monsters are, which one gives what buff and when to kill them. Then, it will take you 4-6 more games to know how to tank/start a fight at the right time, how to use ur ult in team fights and when/how to gank.
Also, this guide is pretty long, and you might get bored while reading it. I've watched all Amumu's jungle videos and read many Amumu guides and almost every guide miss something, maybe due to the lack of time/patience or just the lack of good memory. =P
However, I made this guide the most complete guide possible. I've spent many hours in practice games and about to 5 hours writing this guide, so I hope it helps and makes you a great Amumu player.
Main points are underlined. Read the explanations above them, if needed.

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Updates and Release Notes

v1.0.0.108 - 01/04/2011
Dragon

* Global gold reward reduced to 190 from 240
* Magic resistance increased to 30 from 0
* The on-hit burning debuff now affects the target of his attack but nobody else (previously it afflicted enemies in a cone but ignored the attack target)
* The burning debuff now also reduces attack speed by 20%

v1.0.0.107 - 12/14/2010

Banshee's Veil
* Health reduced to 375 from 450
* Mana reduced to 375 from 400
* Magic resist reduced to 50 from 57

Randuin's Omen
* Armor reduced to 80 from 90
* Cooldown reduction reduced to 8% from 15%

Shurelya's Reverie
* Move speed duration increased to 3 seconds from 2
* Health regeneration increased to 30 from 25
* Mana regeneration increased to 15 from 12

Sunfire Cape
* Upgrade cost increased to 800 from 700
* Passive is now unique


v1.0.0.105 - 11/16/2010

* Curse of the Sad Mummy is now consistent with other similar skills (Dark Binding, Crescendo) and will deal damage to Black Shield
* Fixed a bug where it was disabling enemies for too long
* Now deals 150/250/350 damage initially rather than 150/300/450 damage over the duration.

Introduction

Why pick Amumu?
Amumu fits well in many different team setups, being one of the best tanks in game. He shines in team fights, with his ult and huge AoE damage. Also, he costs only 1350, which is very good for new players and you won't need to sacrifice much to have Amumu as an option when playing a game.

About Amumu
Amumu is a initiator, his primary role is to initiate a fight. His second role is being a tank. A well played Amumu will ensure that your team has the upper hand going into every single team battle. Amumu's ult is a game changer and can turn a lost battle to a decisive ace.

Why Jungle?
Junglers are really good for the team, as you will read above. Also, in WCG North America Finals, Amumu was picked in both games and all Amumu's were JUNGLING!

Pros
- Your team's carry can have a solo lane, while you stay the same level as a normal duo laner.
- You can get gold decently, which is very important to kill dragon quickly.
- You are a really, really good ganker. Your opponents wont expect for you to come, unless they have wards.

Cons
- If your solo laner isn't very good, or if his enemies are really good, he might lose his turret soon.
- Without his ult or low on mana, Amumu can't do much in a team fight or in a gank.
- Amumu can't really push a lane or get a tower down, since his physical damage is very low.

Masteries

1/14/15 ?! WHAAAT ?!? Ok, this is dumb. I'm not reading this, bye. WRONG!
I go with 1 point in offense for my smite. Now, I get only 15 points in utility, so I can get mana regen, improved flash and 30% increase on my neutral monster buffs, which is a must for a good jungle Amumu.

Ok, so why you just dont get all 21 points in utility then?
A better movement speed would be good for Amumu, but there are better masteries. I don't really need a better cooldown, or even a 15% reduced cooldown, since i'll almost always have my Golem's Buff up, and my only ability which is really important to get a reduced cooldown is my ultimate.

Now, I get 14 points in defense, so I can get more magic resistance and armor. I don't pick dodge, since I won't buy Ninja Tabi.

*NOTE: You may put an extra point in Veteran's Scar, and many people will say you're dumb if you want to tank and don't have defensive masteries. I would rather have a point in Greed, which will give me only 6g in 1min, 60g in 10min and 300g in a 50min match. Any extra gold is important, while 15 more HP won't be really useful.

Spells

Flash: Is really good for running away, because you can flash a wall and escape from a gank. Also, you can use it to initiate a fight or even gank. All enemies are expecting you to initiate the fight. Using flash and popping your ult, you will get your opponents flatfooted and crush them.

Smite: This is a must for any jungler. More gold and reduced cooldown are important for you.

Other Spells

Ghost: You can use this to get faster to a lane, it helps you to gank someone or to flee from a battle.

Ignite: Flash or Ghost are more useful for you.

Clarity: You won't need this, unless you are laning. You will almost always have the Golem Buff and will be recalling constantly. In end-game, mana won't be a problem, so, this is a waste. This is useful only if you're laning.

Teleport: I don't recommend this either. You will be jungling, and there are better spells available, but it's up to you. Pick what you feel more confortable with.

Skills

Cursed Touch (Passive): Your passive, reduces enemies magic resist when you hit them, very effective because everything you do is magic damage.

Bandage Toss: Amumu's stun and skill shot. You can use this ability to initiate or even to try to catch someone who thinks he got away. This can be used through trees and walls to pull yourself through them if you have enemies on the other side.

Despair: Constant % Base damage AOE. Does a % of their max health everyone second. Hit this before you run into any fight and always keep this on when u're chasing an enemy. Take care thought, because keeping Despair on will mealt your mana.

Tantrum: Your "spam" move when you are in a team fight. You can use it also to kill some minions and farm some gold/exp. Don't try to spam this on creeps at low levels though, it will make you run out of mana very quickly.

Curse of the Sad Mummy: Amumu's Ultimate. This is one of the best ultimates in the game if used correctly. You can easily disable a whole enemy team and with your AoE damage and % of enemy health, you can both damage enemies squishies champions and take a good % of their tanks. It also allows your team to focus the right guy or even kill 1 or 2 champions while they still untouched.

Items

Since Sunfire Cape has turned unique, the main point on Amumu is not have a core build. It's all up to you to check the enemy team composition and guess what would fit better. The items listed on the initial build is ONLY reccomended for new players. Check the builds above for a better setup.
Also, pay attention on who is getting the solo lane on top (in case they have one) and who is playing mid, because they will be the most leveled champions soon, which means they will probably be the enemy carries. Pay attention for who's fed and who is playing poorly too. If the enemy Pantheon is real bad (1/4 , 1/5), pick up items to counter who is probably dealing the biggest amount of damage, instead of stacking armor right away.
I'm here to give you some suggestions (note I'm giving you just the Core build, you can finish it with whatever you feel it's best):

1. 2 OR MORE CASTERS (Heavy AP Team)

- I go first for a Cloth Armor and 5x Health Potion, then i'll jungle. The Cloth Armor will build later into your Aegis of the Legion.
- After that I go for Mercury's Treads, not Ninja Tabi. I won't need that +25 armor to jungle, and 12% dodge won't be effective as reduced crowd control on you and +25 magic resist is useful agaisnt everyone, since the enemy team will have at least 1 ability power champion, and every champion have at least 1 ability that does magic damage to you.
- Now I finish my Aegis of the Legion. This item is very useful for the team, esp in team fights, which will be starting by then (lvl 10-13). The reason I get Aegis 1st it's because the extra armor and magic resist for all your team will help everyone to survive to the casters. Usually, the team's tank is the guy who has to buy Aegis. If your team already have one, just go to the next item. You can talk with your team when the game starts and say you're going for Aegis, so they don't have to worry about it. Shen will thank you, maybe Janna, but if you have a Nasus on your team, leave it to him, because it fits perfectly in his build. Your Cloth Armor can still turn into a Randuin's Omen, Guardian Angel or even Ninja Tabi. If you don't need any of these, just sell it.
- After my Aegis of the Legion, I go for a Force of Nature instead of Banshee's Veil. The reason I pick Force of Nature is because it gives me a good Health Regen/5, which is great for Amumu, since he's a tank, a huge Magic Resist to counter the enemy casters and an improved movement speed, so you can chase everyone with your Despair on and land those Bandage Toss effectively. Since Banshee's got nerfed, I found Force way better than Banshee's for Amumu, because the extra mana isn't that useful. However, if they have an amazing crowd control and you prefer Banshee's, it's up to you, but I reccomend Force.

2. 2 OR MORE DPS (Heavy AD Team)

- I go first for a Cloth Armor and 5x Health Potion, then i'll jungle. The Cloth Armor will build later into your Aegis of the Legion.
- I keep with Mercury's Treads, because the extra Magic Resist and the crowd control reduced on you is real nice, but if they are really hardcore on that composition (3 melees), go for Ninja Tabi.
- After that, I go for Randuin's Omen, because even after the nerf, his active is a great combo for after your Curse of the Sad Mummy, because your ult will stun then for 2 secs, and after it expires, you active your Randuin's and they get slowed and reduced attack speed.
- Now I finish the Aegis of the Legion, which is very important for my team.
- Please note that it's very uncommon the enemy team have 2 PURE DPSers, like Xin Zhao and Jax, but be aware on your enemy items/champions. I just faced a team with Ezreal, Jax, Trundle (jungler), Kassadin and Anivia (no tanks, yay solo queue on normal games). They had 2 casters, but Anivia was playing real bad, so I checked the enemy team: Ezreal was going AD, Jax is a pure melee AD champion and Trundle is AD mostly. I kept my Mercury's Treads to help with their Casters, but went to Randuin's Omen asap.

3. BALANCED TEAM (1 Support, 1 Pure DPS, 1 Heavy Caster)

- I go first for a Cloth Armor and 5x Health Potion, then i'll jungle. The Cloth Armor will build later into your Aegis of the Legion.
- I keep with Mercury's Treads, because the extra Magic Resist and the crowd control reduced on you is nice. Well, it's a personal prefference, to be honest. =D
- Now I start building Warmog's Armor. I start with Giant's Belt, which will help me to kill Dragon at level 5. Note that if you aren't doing too well, having trouble with picking up assists or maybe even some kills, you can finish your Aegis of the Legion first, and then finish your Warmog. But remember that the sooner you finish Warmog, more time you will have to increase your HP (Warmog's passive).
- Now I finish the Aegis of the Legion, which is very important for my team.
- If they still very balanced (DPS and Caster are the enemy highest levels and both are fed equally), pick up Guardian Angel. It will counter both and reviving will help your team, because it means more time with Despair on. Note that GA's passive is good because you will die in Team Fights only, well, or mostly. Also, you be one of the 1st champions to be dying, because you'll rush and start the fight. If you die alone, the GA passive is just useless, because you will revive and die again. Guardian Angel's passive aura takes 5 minutes on cooldown, and after a big team fight, you would like to wait 5 mins till you have it up again, but most times you just can't wait for it recharges. Just play normally as a tank, initiating and going for "die" first (but remember, not stupidly and alone. You need your team with you).
However, if by now the enemy Caster is very fed and the DPS isn't doing that well, you can pick up some Magic Resist, it's up to you, but Guardian Angel is a nice item for you.

4. UPPER HAND/SQUISHY TEAM

- I go first for a Cloth Armor and 5x Health Potion, then i'll jungle. The Cloth Armor will build later into your Aegis of the Legion.
- I keep with Mercury's Treads, because the extra Magic Resist and the crowd control reduced on you is nice.
- I get Sunfire Cape, because Despair + Sunfire's passive will burn them down quickly. If you have the advantage, this will kill them even quickier, if you're are facing lots of squishies and you don't need that much Magic Resist, Sunfire Cape will give you extra health and armor, while its passive will hurt them a lot.
- Now I finish the Aegis of the Legion, which is very important for my team.

Wards

- Now let's talk about wards. I don't see any wards or very few on solo queues and on normal games. They are VERY IMPORTANT. They give your team a good map awareness and are certainly worth more than they cost. Your team will kill more and die less because of them.

- Remember that you are the tank/jungler, and it's your duty to buy wards and place them correctly, esp if the enemy team has a jungler too. In mid game it would be very useful to ward dragon and mid bushes, then baron and/or dragon and bushes late game. In case the enemy team has a jungler too, consider warding jungle main spots, like the Blue or Red buff. You may ward even your own buff, because he will probably try to steal it if their buff is dead/expired, so, you can set a gank.

- With the new patch, all Sight WardWards lasts only 3 minutes, and they have 1 hp only. So take care when warding, make sure nobody else is around, because 1 hit will kill your ward, and it takes 2 seconds before it goes invisible.

Playstyle

Notes

Jungle spawn timers (after camp is cleared):
- Wolfs, Wraths, 2x Golems: 1Min40Sec
- Blue and Red buffs: 5Min
- Dragon: 6Min
- Baron: 7Min

Early Game

Now the jungle route has changed a bit, but, lets go. Jungle! You will buy a Cloth Armor and 5x Health Potion and start with the Mana Golem. Check if the enemy team has a jungler too, and be aware for any possible ganks, since the enemy will see you have Smite and they know you will jungle. What I do for any possible ganks is sit next to Mana Golem's wall while I wait him to respawn, if anyone comes, I just Flash the wall and run to my mid tower.
*NOTE: When killing jungle monsters, be sure your despair is damaging all of them. To do that, u must stay close to all monsters. Remember to toggle off your Despair when killing all monsters.
* II NOTE: This jungle can be done even without any runes, but that will be a bit harder. I suggest you to try it before in a practice game. Don't try to run from a jungle monster when you feel you are about to die, because if you do so, you will die and won't kill it. Just stay and you will get the kill with 50-100hp.
* III NOTE: This is one of the most important things for junglers. When the enemy team has a jungler too, buy wards, if you can. Warwick and Nunu can kill dragon at level 4, so, ward it before they kill it.

1) The Mana Golem will respawn at 1:55. Attack him, toggle your despair on, pop a Health Potion and use your Smite to finish him off. Pop another Health Potion as soon as your current health potion ends. You should level up now.
*NOTE: Save your smite to finish him (you can know his hp by clicking on him), in case of someone try to gank you or steal it. This way, it wont be wasted.
*II NOTE: If you use your health potion before the actual potion effect ends, you will lose the 1st potion effect. IT DOESNT STACK.
*III NOTE: Thanks to Zenturen, who gave me that tip on the comments. If you start attacking the smaller minions and then go for the Golem, it's easier to kill it and you receive less damage.

2) Head to the wolves, attack the mid wolf, toggle on your Despair and spam Tantrum anytime you can.

3) Head to the Wraithes. Attack the blue wraith, toggle your Despair on, pop another Health Potion, Tantrum them anytime you can and kill it.
*NOTE: Wait a bit before engaging the Wraiths for your mana regen a bit more, so you can spam Tantrum and not lose too much HP.

4) Now, head to the both Golems. Kill them with your Despair + Tantrum.
*NOTE: Wait a bit before engaging the both Golems for your mana regen a bit more, so you can spam Tantrum and not lose too much HP. After doing that, recall for your HP regen.

5) Head to the Lizard, attack him, toggle your Despair on, Tantrum whenever you can and Smite him.

6) Go to the wolves and kill them quickly. Then, head to the wraiths.

7) Head to the double Golems and kill them with Despair + Tantrum. Now, recall for your HP and Mana regen.

8) When u come back, you will see that there aren't monsters in the jungle yet, so, you may hold your mid lane for a bit, so your mid can recall. The wolves will respawn, go there and kill them. After doing this, kill the wraithes.

9) Head now to the Mana Golem, use your Smite and kill him. Now, recall.

10) Now you may take 2 different routes. You should be level 5 by now. I suggest now trying to gank until you are level 7 or 8, if u're 8 already and u're full hp, u can go for dragon, but care, because he's real strong now. If you prefer and stay close to a wall, so you can Flash out if needed. If you can get a little help from who's at bot, it's very nice, since dragon might be warded and it's very dangerous to do it alone.

Now you are level 6 and you're ready to gank. Look for a pushed lane and go for it. Toggle Despair on, Bandage Toss if you can hit them, pop your Curse of the Sad Mummy and Tantrum. all over. There goes your first kill/assist.
*NOTE: You are the tank. Dont feel bad if you don't get kills and you keep dying, because by getting focused in team fights, you allow your team to kill the enemy squishies/dps. It's normal to start with 0/1/4, 1/2/2 and end with like, 5/4/18.
*NOTE II: If you didn't went for Giant's Belt, you can kill Dragon if you're full mana (or with Golem's Buff) and with a health potion by level 6 with a Ruby Crystal. That's a bit risky thought, because you will finish it very low.

11) I usually do my jungle route again, grab the Golem Buff and Lizard Buff before ganking, so I can spam my abilities, slow my enemies and buy my Boots of Speed and a Null-Magic Mantle (which allows me to move faster and tank a bit), but this is up to you.

Mid Game

You keep jungling whenever you can, help your solo laner if needed. You are a better ganker with your ult, but you can still do well without it sometimes. Please note that Amumu is nothing without his abilities, in other words, he's nothing without mana. Grab that Mana Buff whenever it's possible. If your team's carry needs it, leave it to him and try to steal the enemy buff, or just recall and save your mana. Kill the Dragon whenever he's back, or ward it at least, if you can't kill him at the time. Finish whatever you went for, Mercury's Treads and get an Aegis of the Legion. Team fights should be starting by now and your time to shine has come.

Late Game

Team fights are exploding all over the map. You would like to have a great map awareness to avoid ganks, so ward both mid bushes, or maybe dragon. By level 15-16, ward the Baron and the lower mid bush only. In team fights, be aware of how is it going. Don't start a fight outnumbered if you think your enemy has the advantage. YOU ARE THE INITIATOR, IT'S YOUR CALL WHEN TO START A FIGHT OR RUN. You can win a game or lose it. Don't rush like a fool, and don't be a ***** either. Don't waste your ult in 1 enemy only, unless it's needed to get the kill (like in a gank). Save it for big team fights.

TLDR - Main points are underlined. Read the explanations above them, if needed.

Thanks to Stellar Guardian, who helped me a lot with this guide and to Vertical Dsb, whose Amumu's guide helped me when I started playing him.

If you downvote, please state why. It doesnt help that you downvote without an explanation and since you have to be logged in to vote anyway, please take the 2 seconds to leave a comment.

If you read it all, which I doubt (I wouldn't read it either, lol), thank you for your time. Please vote and comment !