User blog comment:TheTobarMethod/A New View On ADC's IMO/@comment-3541335-20130211221737/@comment-92.161.221.24-20130212005555

amumu is a tank...

do remember   their role depends on what you build on them

a champion and his kit just limits the number of roles viable on  them

you can build amumu tank

you can build amumu tanky ap to give the team some more dps

you can build amumu as an ap carry ( he does have great ap ratios) and  engage  with him then zhonya

just like nocturne :

you can build him offtank/bruiser

you can build him assassin ( in games where an  mf    or other low escape carry is fed assassin noct can  stop in their track  an important target)