tried this out pretty funny when you get you ult off early game it wreaks but some things on item sequence rush tear and get archangles first so you can stack it up then LB and cap.
also if you want more defense change from zerkers to mercs and for the lack of magic pen get soc boots also you can change some runes for magic pen and i think you would get better results.
anyways still a very nice guide and it works pretty good.

very interesting i like the 3 k ult im going to have to try this with a friend playing amumu and tell them to fucos tank lol and vote if its any good :P

Thank you for your view Kibblinator! It is very much appreciated. The reason I start for it is simple. First, it is one of the items that has a useful ability other than AP, which is important when trying to keep as balanced as possible given you're main goal is to mass AP. I get magic resist for one, which to me is important, because as a hit and runner, my main fear is ranged/magic attacks,and more likely the latter will occur more often, so having protection aginst that is good. Also, the added attack boost is nice early on as well, as it gives me a better chance to take out turrets early on, whereas an added boost to my spells doesn't help against turrets.

I disagree with rushing Lichbane, IMO it should come later after you have some AP. this isnt how i would personally build Nunu, but the build is well written and I see no other reason to downvote past my own opinion, so you have a +1 from me ;D.