Hello everyone! :D
I decided to make this build to help some people jungling with Amumu.
Initially I started by watching some streams. Then, I perfected my build according to my runes.
This is a short Build but have the essential.
I hope this build helps you, the same way help me!

EnjoY,
KlaudioPT

Well, my runes are simple!

-» Marks: I have Magic Penetration, just because I usually don't buyVoid Staff. So in early game, this make me more strong as jungling as ganking.
-» Seal: In game, most of the items are for defense. So i need some damage.
-» Glyph: Cooldown Reduction. This is the most important in my build. This can help me a lot as jungler, and in teamfights/ganks. Why? Just because, I usually gank when my ultimate is ready. So with CR, i can gank more and more efective.
-» Quintessence: Just damage! (More damage in early game).

My Masteries are 9 OFFENSE and 21 DEFENSE, why?

Well, in Offense i take the same advantages of my runes, Ability Power, Cooldown Reduction and Magic Penetration. It makes more strong.

And in Defense, just because in early game i need some defense so make some risky ganks and to jungle better. So i take some defense against minions to jungle. Magic and Armor resist to gank diferent champions.

OK, i will explain the order and what you need to buy and sell buy steps.

I start with, Cloth Armor and,x3 Health Potion.
Explanation: It helps you in jungle. I usually do Ancient Golem -» Wolfs -» Wraith -» Golems -» Lizard Elder.

Them return and buy, Boots of Speed and,Doran's Ring.
Explanation: This will help you ganking. Now you are about lvl3 and you have speed, buffs, and damage. Try MIDLANE, if is not possible ganks other lane, but don't forget helping MID most.

Now buy,Doran's Ring and, Sorcecer's Shoes.
Explanation: This is not relevant, but give you more ability power, and mana regen. That's why i buy x2. To help me having better mana regen, and more damage. And finish your boots with sorcerer's shoes, to have some magic penetration.

Now buy ,Abyssal Scepter.
Explanation: Your first item need to be this. Why? Just because i usually gank mid, and mid champions are usually AP. So it gives you magic resist, some damage to gank, and reduce enemy's magic resist. it's the perfect item! Don't forget to start with Negatron Cloak, you already have enough damage.

Now buy ,.
Explanation: Now you have enough Magic Resist, so you need some Armor Resist. This item gives you armor and health. And at same time gives you more damage.

Now buy ,.
Explanation: Now this item is more to your team. You have magic and armor resist, and this item help your team having some defense when close to you. And at same time gives you more health, armor and magic resist.

Now buy ,.
Explanation: This item will give you a little more Ability Power, and Health. And at same, slow enemy's movement speed. Good when the enemy is fast ;)

Now buy ,.
Explanation: Now you have strong defense, and good damage. But sometimes, when you start teamfights, you can die fast (when enemy team focus you). So it helps you survive. And when you have Guardian Angel, the enemy team never focus you. This is good for you, because you have enought damage to help your team.