This build makes Amumu IMMORTAL!
The items you see on top are the normal items that I choose but they may differ according to the enemy team. For more info check the Items Chapter below.

I think that Amumu is the best tank in the game because he has massive survivability + great damage.

If you have any questions please write a comment below or add me on LoL.eu - Gabb1995

So for Marks I choose Magic Penetration for some extra damage withBANDAGE TOSS andCURSE OF THE SAD MUMMY.

For Glyphs I get some Magic Resist Runes or if you want you can get some Armor Runes aswell. Never choose flat runes.

For Seals I get Mana/Reg Runes because Amumu totally needs them forDESPAIR. For more Mana/Reg get the blue buff everytime! Its totally useful for Amumu.

Normal

At start always getRegrowth Pendant andHealth Pot.

Make sure that when you recall first time you have enough money forPhilosopher's Stone and aBoots of Speed. Then upgrade intoBoots of Swiftness. I get Boots of Swiftness because Amumu needs that boost of speed to catch up to enemy players and stun them + use despair on them.

Now get 2 Regrowth Pendants and later build it intoForce of Nature. Then getSunfire Cape which is very important for more damage when combined with despair and also for jungling.

At late game you getAegis of the Legion which gives you more armor, magic resist and health and gives bonuses to allied champions aswell which is important as you are not the only one in the team.Frozen Heart is important to get aswell as it gives you more mana + more armor and it gives you 20% cooldown + it reduces attack speed of nearby enemies which helps a lot.

VS. DPS(Melee Characters)

Get the regrowth pendant and hp pot and philosopher's stone aswell but instead of boots of swiftness you may get theNinja Tabi for some Dodge Chance.

Instead of Force of Nature get aWarmog's Armor for massive health and hp regen. Get the Sunfire Cape but then instead of Aegis of Legion get theThornmail and then instead of Frozen Heart get theRanduin's Omen. Always start with Philosophers Stone.

VS. Mages

You may getMercury's Treads for that stun duration reduction and magic resist. And instead of Frozen Heart getBanshee's Veil.

During the first 5 levels I get 3 levels ofTantrum so you can get a lot of damage for farming and killing laning champions.
After level 6 I max outBandage Toss for its stun and damage.
Then I max out Tantrum and lastly Despair.

In fights I first toggle despair then Bandage toss, Tantrum and Ulti then you bandage toss again and tantrum.

I chooseGhost andIgnite.

Ghost is very important to escape and to catch up to people. An alternative may beFlash.

I take ignite for that extra damage and first blood. Ignite is good for every champion as it reduces healing of champions.

If you dont have the mana regen runes you may takeClarity. If you're a first timer takeHeal and practice versus bots. Now theres the new Co-op vs AI game mode which may help you.