Ok so I recently decided to unlock Amumu so I could be a present YAY lol. This build has worked EXCELLENT for me so I figured I'd share it. Like all my builds it prolly has flaws and people gonna thumb me down etc but whatever. Keep in mind I normally do 3 v 3 and not really 5 v 5 so this build is untested in 5s.
Summoner Skills: I take Ghost and Exhaust. I like these 2 for escape and or chase utilities. It has helped me get away alot as well as got me a few kills to keep em in range of my despair a little longer or give me a chance to throw another bandage. Depending on your playstyle you may want different skills.
Masteries: I go 9/21/0 I really love the defensive tree for Amumu I think it works wonders for that extra defense and helping keep you in the fray a little longer in the attack tree I go for ability power and magic penetration to help with my abilities. Notice I took Cripple to help my Exhaust instead of 1 point in Deadliness.
Runes: Now I am not lvl 30 so people gonna run their mouth but being lvl 25 using the runes listed minus my lvl barrier still works for me. Scaling AP Glyphs are beast at making your skills hurt a little more along with the magic penetration Marks. Mana regen seals are nice top help with mana consumption again the scaling ones are so much better. I went with flat Quints for Ability power cause frankly the scaling Quints are barely double the AP IF that at 18 and I rather have the boost early game and keep it flat than scale for a small amount of gain.
Skill Sequence: Ok I start with Bandage toss and untill I absolutly have no other options I don't level it instead I work on Tantrum And Despair. Tantrum is also a REALLY awesome skill Besides the fact the passive reduces your damage taken which is beast you can activate it to do AoE damage as well as each time you are hit it reduces Tantrum's CD 0.5 seconds making it semi spammable when you charge into a fight against a Champion. *NOTE* This chews the **** out of your mana so i don't suggest spamming on minions I occasionally hit minions for last hit but save them mana over all for champion fights. Despair is sooooo yummy especially against other tanks. I went against a Tank stacking HP and armor and dropped him so fast he wanted to report me for hacking. This is also Great for when an enemy is running if you have it active and use Ghost but aren't quite in melee range yet it can tick HP off of them as well as when you toss a bandage in on them. Take your Ultimate whenever you can. This is such an awesome skill This is bastically a circle AOE Stun with a pretty big range outward from Amumu. This is great for ganks or just getting in and getting people dead. I like to Turn on Despair, Bandage toss into a champion (especially if they are grouped together) and blasting Curse of the Sad Mummy Despair starts ticking and you start hitting and using tantrum. Your team should be backing you up cause its likely that if you try to do this against an entire team you might get 1, 2 if your good but overall you prolly gonna die REMEMBER assists are kills too just cause you don't have the most killing blows doesn't mean you didn't stomp a mudhole in someone.
Items: First off not all games require the same build I often change order of things at times or make substitutions based on who I am up against.
I like to start with a Doran's Shield This is sold when you have Sunfire cape or to complete it I.M.O.and a HP Potion I follow this with boots of speed cause normally my first trip back I don't have much huge cash and Amumu needs some run help. I get a Sunfire cloak. I get it in pieces if I have too this is a great item to stack with Despair and gives you that extra HP boost with the Passive DoT. Depending on the Situation I get Sorcerer's Shoes or Mercury Treads. If they have alot of AP people I take the treads for added resistance otherwise I go Magic Penetration. Next I follow this with Thornmail More armor and more DoT when hit with despair and sunfire going off as well this is killer for the foe that hits you. Next I like Force of Nature. People can argue wityh me about it but I like the HP regen keeps me on the field longer and having extra Magic Resist isn't so bad. People tell me "Get warmog's instead" well it takes too long to build and I like this better you want warmog's then by all means get it. Abyssal Septer More Magic Penetration YUM more AP for harder hits YUM Magic Resist well hell you are an all around tank stacking all types of armor making you a mini emo brick wall. Finally I like to finish with Rylai's Crystal Scepter. To be honest I haven't had a match last long enough to finish my Abyssal Scepter but I figure this would be nice for more AP more Health and The passive slow firing off from using Tantrum and other abilities would be nice if your game has taken this long (I assume in 5 v 5 its very likely you can construct this) I would like to note sometimes I grab an extra Health Potion on trips back while building Not too often but occasionally I do if I think I may need it DO NOT UNDERESTIMATE these potions I have popped one before starting a bandage toss combo and have assisted in taking out a POWERFUL team with regen keeping me alive, sometimes those extra seconds mean EVERYTHING.
Feel free to comment terash talk me and thumbs down me. I hope this helps some of you that use it