Give Amumu the Alistar Treatment
https://i.ytimg.com/vi/rfGkK9lyHpQ/hqdefault.jpg
Similar to Alistar, replace Amumu's passive with his w. His new passive: every time Amumu is hit by an aa he cries dealing damage in a area around him. The damage would be lower than his current w but still high enough to have an impact. It keeps true to his character and would provide some power with obvious counterplay. I made a post about some reworks I had in mind and while most of them fell flat this one everyone seemed to like. This also opens up his w for a cool new ability to shake up his VERY linear gameplay.
So... What do you think? I know Amumu is fine and other champs need reworks more but this might be a start in putting him into the right direction. Comment on any tweaks you might have to this passive or ideas for an open w on his kit.