This build is made for amumu to be a dangerous tank. We mainly focus on armor, health, magic resist and ability power. Depending on the situation we increase magic resist or armor more then usual. We did not change anything at the masteries or runes as you can't always know which kind of opponent team you'll have (like in normal games for example). We only change the items to show the difference in build and to show you which build is usefull depending on the situation.

We start of with our basic build adding both magic resist, armor and AP to our amumu. The reason is to have a balanced base to work from since teams usually have both dps and AP champions.

Same thing as the runes we increase stats needed by mages and tanks since we are a tank which uses AP to be dangerous. For more details you can check the mastery trees this time.

For items both builds start of with the same itemfor extra health. Early game we stay defensive and assist our partner by dealing damage/stun and using summoner spells to weaken opponents. Then once we can we return to base and upgrade it intonow we won't have to spare mana and we can take small risks knowing we get health and mana on lvling up. With the catalyst we can stay defensive for quite some time without having to leave the turret/lane. This is the best moment to farm while your team has the upper hand on your lane due to the early kills gained by teamwork. When you finally return to base you should be able to get your boots and upgrade the stone intowhile we grow with the rod we keep farming and supporting our team to earn gold. Once you got enough you go get. Now its time to decide your build. If most of your opponent team (min 3 ) are meelee users you go for the items shown in the vs dps build. If not then you go for the anti mage build. Only difference between the builds is the armor and magic resist. If fighting a mixed team always take the build which is best against their strong champions.

ghost: to speed up making you able to keep following running opponents with despair, dealing them damage.
exhaust: usefull as support for your partner early game, later on usefull for slowing down opponents to keep them withing despairs reach.

other useful spells: clarity, ignite, heal (heal only early game , later on its worthless)

pro's:
- both builds have alot in common making it easier to switch between them if necessary
- you can combine the build to make the best amumu for each situation.
- alot of defense (armor/magic resist)
- decent health
- decent AP
- supportive tank champion with constant AoE damage making him usefull in team fights.
- team player
con's:
- still fairly slow
- can't be better then the team as he needs their support aswell.

First time i had to make a double build, i hope you'll find it usefull and feel free to combine parts of both builds to make the best amumu for your team. Comments, feedback and advise welcome below ^^