Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
I've been playing a lot of Amumu lately and felt the need to pass on a build that isn't aweful like most the ones I've seen prior.
It's an aggressive tank build that revolves around magic penetration. It really puts the hurt on the opposing tank (and the rest of their team as well).
So this is what is neat about Amumu and magic pen. He has a passive ability which makes all his attacks decrease the targets spell resistance by 20. As many know, the way spell pen (and armor pen) works each point becomes more value the more you get. This makes Amumu getting spell pen an intimidating venture.
Let's look at the math:
This is the equation for damage dealt (A) where R is the target's resistance, S is the skills description damage, M is the skill's damage modifier for ability power, P is caster's ability power.
A typical hero will have a base spell resistance of around 35. Amumu's passive ability reduces this resistance by 20. Leaving a resistance of 15.
Assuming S*M*P=1 to look at the amount which is bypassed, originally the hero would only take 74% if the magic damage delt to him. After Amumu hits him with one attack, he will now take 87% a 13% difference. Now say Amumu invests into spell pen runes providing an additional 19 spell penetration.. He now deals 100% of his base damage to the target. 26% more damage.
First I'll talk about summoner spells. Amumu needs cleanse, its that simple. As a tank who's one strong point is his ult, he needs to be able to cast that ult through anything at the right time. This means removing stuns-hence cleanse. Unfortunately, cleanse no longer removes silence mechanics, but its still by far the best summoner skill for this character.
The second spell is up for personal preference. I chose ignite because, lets face it. Amumu fails at the early game threat. In order to protect yourself and your partner in the early levels I find ignite is just enough to keep the enemy honest. You will still need to lane with someone who can harass, but with ignite you can burst someone down if they over commit.
Next lets talk spec. More gold is always nice but 5% xp means that you will get to that formidable (if not overpowered) team killer tank faster. The rest of the spec is just your typical tank setup. Notice the dodge runes and the dodge skill, this is to help you keep up with enemies since you have spell pen shoes instead of movespeed 3 boots.
Despair is Amumu's "Best" ability by far. Despair (5) by lvl 9 is the best way to go I've found. Having the stun is crucial for harassing and protecting but more than 1 rank is not a good idea. Tantrum is nice for getting killing blows on creeps and for harassing but doesn't have the damage output for an actually battle so get one point in it early then leave it alone until level 8 when you can only choose between it and toss.
Almost every guide I've seen rushes tantrum over despair (because of farming i'm assuming)however, despair puts out a much higher dps in almost all situations.
Lets say you are fighting a target which isn't a tank, yet a fairly solid dps character.
At say level 8. That means your target has about 1k hp. This means we would be comparing despair (4) verse tantrum (4) dps.
Tantrum (4) deals 150 (plus ap modifier) damage every 12 seconds -.5 seconds every time attacked. An average lvl 8 attacks about 1 time second. meaning on average tantrum (4) would go off every 7 seconds. 150 damage/ 7 = 21.5 dps
Now despair, despair (4) does 20 damage + 2.4% of there make health (an additional 24 damage) per second = 44 dps. Over double.
Now given, you can't harass the same way as you can with tantrum, but there are advantages to despair. You can kite pursuing enemies, and you can put out much higher dps when protecting your partner (not getting hit).
Spell penetration is the point of the build. The more you have, the better it is. So get as many spell pen runes as possible. For the seals get dodge. It will help survivability as Amumu has considerable less hp than many other tanks.
Amumu is a great laner if he has mana to use. A stone will greatly help Amumu farm, push, and harass effectively. A stone will pay for itself via gold per 5 and extra killing blows in about 7 minutes on average. After this point it is all profit. I then get spell pen boots. Then a sunfire cloak. Then a banshee's charm. Then a second sunfire cloak. Finally I get a guardian angel and Force of Nature.
At the very end of the game, if the enemy team is very magic heavy get a force of nature. Or if your having trouble tanking get a warmog's. You have to be careful when doing this because you now have only your base mana regen. Only do it when you have everything else and then don't use any mana to kill creeps unless on a major push or having the golem buff.
As I mentioned before, Amumu is a weak character early game. Because this is true, I only play Amumu 5v5 because 3v3 has too much emphasis on early kills and ganks. Even in fives Amumu must be ever weary of incoming ganks and lane conservatively with his partner until at least lvl 6. You should keep yourself over 90% hp at all times, keep mana for toss and only use toss defensively unless a kill is nearly assured. Keep mana high, 60%+ so that if a fight does break out you can hold despair out through it and keep tantrum on cd. Don't worry if you aren't getting killing blows on creeps in the first few levels. Your partner will probably hit harder than you and be farming all your gold but that's ok. Come lvl 7 you will get more than enough killing blows to compensate your slow start and at that point you will have mana regen enough to support aggressive farming, hp regen enough to tank mobs and harassment and your ult to scare the pants off anything that would otherwise try to commit to kill you.
As soon as you get 600 gold get a stone. The only exception to this is if you have a lane to yourself and would lose a lot of xp doing so. (This only happens if your partner is gone shopping or is dead)
Once I have my a sunfire cape if there are many mobs to be had jungling, I clear out the jungle on my side of the map (and the dragon if I feel safe doing so). After getting a easy lvl from the jungle I grab spell pen boots and focus on trying to start a team fight.
Usually in mid, I head up the assault. With everyone else defensively placed behind me.
Usually the enemy tank will be doing the same and I'll rub shoulders with him a bit. The enemy tank will not do the amount of damage despair (5) does to him. He will retreat allowing the team to continue to push, or someone else will come in to help him (sometimes the whole team.) You want to get at least 3 people in your ult. At which point your team will jump in and gank one of their squishies. If you push them all the way to their turret your ranged dps can come in and pester them and do progress on the tower. Don't go far into the tower's range yourself. Eventually, they will try to gank your ranged dps, or the tower will fall. Use toss to defend your dps allowing it to retreat to the support of your teammates. If they commit use the ult and dispose of them readily, if not rinse and repeat.
If your ranged dps takes too much damage or runs out of mana, fall back, farm more gold then try again. Importantly, do not waste your ult unless you can get at least one kill, because as soon as you do, you must go on the defensive until the cd is up again.
If they have a singed or a blitz, this strategy gets a lot more difficult, as your ranged has to be careful to not get pulled where he doesn't want to go. If you have a heimer, this strategy works great as he can harass a tower from a long ways away and under turret support. This forces the other team to attack you away from their tower, against a fortified position which is hardly fair.
Most ideal teammates for Amumu are:
Unfortunately, none of these make ideal laning partners.
Most ideal laning partners:
People you should not lane with, at all costs:
These character either don't do enough damage to harass, are too squishy to protect, or do not have solid crowd control mechanics for escape.
Avoid laning with the characters if at all possible, and if you do have to lane with them. Allow the creeps to fall back to your tower and fight them there.