Hey, this is my first guide. I've played almost exclusively Amumu for a while, so I feel I have enough knowledge to make a guide on him - although I'm by no means godly. This guide was inspired by Amumu - the Misunderstood Mummy. I felt there was a couple problems with it though, mostly how slow he was and his lack of magic resist. Basically this guide sacrifices a few things from the previous build to balance out those two things.

Early game Amumu can find himself with quite a mana problem if you don't conserve and use your abilities wisely, and even mid/end game if you find yourself in a lot of team fights blowing everything. While at that point you should almost always have Golem, I particularly like the lasting power you have early game, which can easily make a difference for the match as a whole.'

The health regeneration/health runes also help early game, and keeps you from completely getting destroyed by champs with lifesteal/spell vamp. As a note, I find early game those specific champs pose the biggest problem with me so these runes are something to seriously consider using. Not to mention with the majority of champs that don't utilize those mechanics, you end up being able to stay in your lane while they return to base 1,2 or even 3 times. This obviously provides a great advantage.

As for the cooldown reduction, I feel that it's especially important end game, where your Ult can make or break team fights so I opted for Celerity (7.02% CD reduction at 18) instead of Focus (4.92% CD reduction constantly). I'd rather have extra late game, because early game you really don't have the mana to be spamming attacks every time they're up anyway, and as I've said his Ult is godly late game. I did have Vitality but the 145 extra health in my opinion doesn't outweigh the CD reduction. I built this Amumu to be very fast, and have a fair amount of magic resist, so if you can't get away, it's going to be a lot more than by 145 health and is probably by a whole team chasing you down. He already has an extreme amount of health to begin with.

As should be obvious, Amumu is a tank champ and I don't condone the use of Offensive talents. Some people (rarely but I've seen it) have built him as a DPS, and even I've tried it back in my newer days (when Sunfire capes were stackable). It was fun, but he certainly is not meant to be built that way and his tanking is far better. Don't do it.

I've seen some people take Defensive Mastery but I don't see the point. He has no problem with minions hurting him, by level 10 he can jungle everything besides Dragon (which he can do by 12 anyway) and he can tank Baron without a problem.

Strength of Spirit is pointless as he doesn't have the worlds best mana pool, and this build has more than enough health regen without it.

If you really felt the need you could take Nimbleness instead of Greed but he doesn't truly need it, and the little bit of gold can make a big difference early game and that one extra item you may be able to get on returning to base could give you a kill.

You can distribute Expanded Mind and Awareness however you want, but everything else in my build I find is necessary.

Here is where he becomes a different animal from my inspired build. I find starting with Regrowth Pendant into Philo Stone is the best way to go, since you will be building a Shurelya's at some point, and gives you yet again early game lasting power.

For shoes you can get either Ninja Tabi or Mercury Treads. I will normally go for Ninja, but if you find yourself having an issue with a mage on the enemy team or the team is mostly composed of them, you can grab that instead. Both help Omen, and both are great damage mitigation. It all depends how the match is going.

The next three items and their order are a matter of preference and what you're up against. Heart, Catalyst, Negatron is my default order but if you need a higher tier item early on for whatever reason, you can build it first. Catalyst and Heart are best taken early on though and when you build into their better items the effects are gone, so best to abuse them while you can.

Next is Force, Shurelya's and Banshee. Again, you can take these in whatever order you see fit for the specific match. This is where he starts to shine. Once you have these 3 items you become a power house. Mages hardly hurt you unless they were fed, you're super fast, and you gain a lot of health regen from force so if you're hurt, go run and jungle for a bit and regain your health, negating the need to run back to the Fountain after every team fight. You'll always be productive and these 3 items lower your downtime substantially.

Next you will go for Omen, which lowers your CD reduction even more, and will help in chasing/slowing the retreating enemy/team so the kill will be almost definite.

This is quite an expensive build so this will normally be as far as you get, but if you need a last item the choice is between Sunfire and Warmogs. I will go for Sunfire 99% of the time, since by late game Warmog doesn't have the time to be maxed. The only time I will take Warmog is if it's a close and long game and I need the extra health/regen to survive team fights. The better choice will almost always be Sunfire though, as it provides a fair amount of health/more despair type damage and is more cost efficient.

I can assure you there will never really be a time that you will need/have time for anything past this, and there's really nothing else to get or sell to have room. If this does happen, go ahead and by whatever Elixir you need depending on what is going on.

The first skill is a choice between Tantrum and Bandage Toss. Don't ever get Despair first. I personally prefer Tantrum since it's more mana efficient and helps you get last hits early on. That extra gold means everything, so don't be afraid to use it to kill some minions. You'll also hit level 2 slightly quicker, which will allow you to get Bandage Toss second. You can also hit and run with Tantrum on a champ that first level and still do a bit of damage. Bandage Toss alone that early I feel is useless against champs and the damage and subsequent hit is not enough damage to outweigh the last hitting.

You'll want to max out Tantrum as quickly as possible, only not taking it when it's available at level 6 in favor of your Ultimate. Normally I will stay in the lane until level 6, and then go back to Fountain to get items and heal, then come back with my laning partner and get a kill or two using all my abilities. You'll want to have Clarity up best case for that because the mix of your Ult, BT and Tantrum will leave you with nearly no mana.

As I BT I will put Despair on to get the max damage on the enemy, then tantrum and melee them. Before you're fast enough to outrun anyone, BT is best used to close the distance between you and them. When I Ult, I'll make sure my BT and Tantrum are up. Use it, Tantrum with Despair on, and as soon as the Ult wears off, BT them. and Tantrum again as soon as it's up. If they are low health and it's safe, chase them with Despair on and try to get them before they're too far away.

Don't ever use your Ult to KS or on one enemy, unless they have a Snowball item and you're sure using it will get them dead. Later on it's best to save it for team fights when there's 2 or more enemies. It's rarely used as a good escape mechanism, but only if you know you'll get away by using it. With Golem and my CD reduction items it's on about a 70 second CD.

It's also a good idea to learn where you can BT through walls. It's a situational way to use it, and you may never get the chance, but it can be a life saver/chaser one day.

You can get Golem at about level 8-10 depending on which items you have. It's something you'll almost always want to have, granted it won't cost your team a death. If there are people hitting your turret near you, don't sit there and go get Golem.

At around 11-12 you can solo Dragon and when time permits it, it's a good idea to go get. BT on CD, toggle despair and melee and Tantrum your way to killing him.

When there's a bunch of minions and they're all low health, use Tantrum to get a bunch of last hits. Don't ever be afraid to use it for that reason, especially early game.

This is my first guide, and if I missed anything/got it wrong feel free to make suggestions/constructive criticism in the comments. I hope you enjoy the build and have fun. :)