Awesome. Seriously. Thanks for putting this together.

Amumu was the first champ I purchased, and I've always played him as a tank/support. I stopped playing back when Fiddlesticks ruled the jungle, and haven't been able to get a good build together since I got back into the game. This will help a lot.

good

I'm not all that good at coding and tried to keep it simple yet okay to read. :P I'll do my best to spice up the code though, if you want.

You probably have a good point on maxing Bandage Toss second. I'll experiment with it and later on inform you what I liked the most.

As for lucidity boots, if you have a full build with this guide you already go a little over the cooldown reduction cap, so in most games boots of lucidity wouldn't be worth it. If you swap out Frozen Heart for Spirit Visage or something, you could indeed opt to go for lucidity boots however I still think the tenacity / auto-attack damage reduction is more important.

Interesting guide. Amumu support is something that I think I underestimate too much and looking at this guide made me think twice.

Just a few suggestions. You could try and add some text effects via code just to spice up the paragraphs. Maxing Bandage Toss 2nd might also be very effective as Despair only becomes really strong late game. Lower cooldown and higher burst on your main engage spell would probably be very strong. Also, what about Ionian Boots of Lucidity? They help with Curse of the Sad Mummy's incredibly long cooldown and work well with your Bandage Toss for engages more often, especially when you're going to max it last.

Nice guide overall. The build is really strong and well explained.