Not Updated For Current Season
I choose flat HP quints for easier jungling.
I choose flat magic pen reds because they're the only good choice for AP champs.
I choose Armor/lvl and MR/lvl seals and glyphs to make up for lack of defensive items in the build.
I choose not to go with standard 9/0/21 AP build for a number of reasons.
First, we will be jungling, so we want to get the extra HP and damage reduction from the defense tree.
Secondly, we basically gain no benefit from the Archaic Knowledge talent since Amumu's passive is so powerful that it makes much more sense to stack flat magic pen as opposed to % magic pen.
And finally, Amumu gains less from CD reduction than most champions, so going deep in the Utility tree isn't very enticing. One of his abilities (Despair) is a toggle and another (Tantrum) refreshes pretty rapidly in many situations.
Here's the meat of this build. Many people like to play Amumu like a pure tank, i.e Sunfires, Randuin's, Force of Nature, etc. It is my opinion that the only champs that should gear for pure tanking should fall into one of these three categories:
- Those who do NOT scale well with offensive stats ...
- Those who DO scale well with defensive stats ...
- Those who know for a fact that enemies will be attacking them ...
If you don't fall into one of those categories, you are not maximizing your capabilities by wearing all tank items.
Now, that being said, we can't just go into battle with 1700 HP and base MR/Armor because the fact is that Amumu is a rare breed: a melee range AP champion. Luckily, there are plenty of AP items with tank stats on them.
We start off with boots and 3 potions. If you don't have HP runes, you may want to recruit some teammates to assist you in killing the blue golem at level 1, or if you really want, go with the standard Cloth Armor + 5 health potions.
Catalyst the Protector
Next we build the Catalyst. This item is a godsend for Amumu, especially if you lose control of your jungle after the first sweep or have someone else on your team that needs blue early game. With this item you save yourself at least a few minutes of going back to heal over the course of the first 15 minutes of the game, which is huge.
Then we build the Catalyst into Rod of Ages and also finish off our Mercury's Treads. You can choose a different set of boots depending on your preference or opposing team's setup.
At this point, you need to adjust this build to counter the opposing team. If the opposing team isn't stacked AP or AD then you can just build exactly what is shown. However, if they are stacked AD, you should go straight for a Sunfire Cape. If they are stacked AP, you should go straight for a Banshee's Veil.
One last point, you may want to build the Rabadon's Deathcap earlier if you're doing well mid game, perhaps after the Zhonya's. This way you can put away a team by going on the offensive and it also allows you to kill Baron much faster, kind of a "snowball" effect.