If there is mainly magic casters on oppen. side, dont buy thronmail :D but guidien angle
Also take magic resist boots if mainly spell casters insteed of 3 m. speed :D
Reason for Summoner spells:
Heal is very good early game, and is still supporting late game.
Exhaust is good for disabling incoming damage, or slowing champs if charge anit ready.
I mainly spec tanks spec.
I go for mana and hp generation, as you will be needing mana and hp, both early and late :D
Also i spec for Exhaust for easier kill :D
I stack for Hp and im mainly need it for charge, also in stacking Magic pen, for more damage with AoE abilities
Mainly you will be having to ways to play early game as Amumu.
One way is to have a team mate going Jungle, leaving you to defend your turret, This may sound boring, but its very good for your team. also you can kill Oppen. Champs. easy if they attack you infront of turret, if they do, charge them, this curse them to be stunned and you can easy kill him, heavly supported by turret.
You will have your team mate by your side and your only job is to charge and stun oppen. champs. and make your team mate kill them. At lvl 6 you can easily kill 2 champs. using your ultimate.
You would want a nuke as team mate, not a stunner.
You should have started to ******** at this part of the game, your only job is to charge then oppen. group, use ultimate having your cry ability toggled. The sunfire cloaks are supporting your AoE per secound damge heavly.
And if you are against alot of melees your Thornmail will take them Out.
Please Comment & and give tips, so i can keep it updated :D
Gl and Hf