nice guide....tough you can change one item with the "ice shield" ....would be super tanky and can let you spam skills even more faster...depending on the game now....

@Isthatok
- BTW, I am aware of Amumu's recent nerfs, in fact, that gives more reason for a proper guide - to make sure that no mistakes are made, which now would prove costly.
And about the nerfs, Tantrum and Despair are Amumu's main + constant damaging AoE abilties! and the mana cost of Tantrum has been decreased! Although we wont see Amumu instakilling AD carries anymore with a nice Q-E-R combo... he can still provide a great deal of damage.
I would however recommend to go for a Voidstaff instead of the WotA, due to the nerf in Q and ulti, which are some of the best spellvamping tools.
The nerf in the passive is trivial. You don't often go around autoattacking in clutch teamfights, mking sure to instead keep up with the enemy and damage them with ur AoE.

A very thorough and feasible guide. Looking forward to applying your tips to my gameplay!

Sorry! I thought that was done automatically by the site ^^... editing as we speak!

I guess it's logical for a pure AP build even though I don't really recommend going against the meta, especially with the recent nerf. In any case, I suggest highlighting important keywords to make your sections look less like walls of plain text.

Voted +1 for encouragement.