This is my first build so please give me constructive feedback. This guide is still under construction i just went ahead and posted it because i wanted feedback from others and to see what others results were from testing it.

I made this build because it seems most of the full tank builds on here were jungle builds and i don't care for jungling too much.

Flash: pretty self explanitory. Great for escaping or chasing (Only chase if they are mushy and have below 50% health, if there is only 1 left and your team is right behind you, and/or they are almost dead.

Teleport: I use teleport to help get me back in the lane faster early game, and to help me get to other lanes to help if they are in trouble or into team fights faster. If you don't like using teleport then switch this out for ghost or heal.

Also since ghost and flash are both escape moves i should also note that your bandage toss if used correctly can be used to grab monsters in the jungle to pull you through walls to help you escape easier.

I don't have a lot to say about this but Ive noticed that some of the other tank builds use put 2 points into evasion and 2 points into defensive mastery. I personally don't care the dodge much as Amumu so I usually go for strength of spirit which i find (with my items make up) much more beneficial than dodge. the only reason i put 1 point into defensive mastery is to get further into the defensive tree.

I also realize that Ardor isn't useful since you don't get any AP but i have it just in case i do get abyssal scepter. If you don't want to use it then just add another point into defensive mastery and 2 into evasion.

Also i use expanded mind because Amumu seems to run through mana fairly quickly but if you don't like this you could just put it all into awareness and keep 1 into expanded mind or put 1 into utility mastery or good hands (I would prefer utility mastery) and make sure to get the blue buff as often as possible.

Also if you use ghost instead of then get haste or if you use heal then put a point into good hands.

I made this item build so that it would be fairly balanced but as with any tank build you should build according to the opposite teams make up.

The only 2 items I feel that shouldn't be changed out for situational items are merc treads and sunfire cape. I find merc treads to be very helpful due to the CC time reduction even if the team mostly consists of AD.

On most champions I don't care much for sunfire cape as much as I use to since it isn't stack-able anymore but since amumu already has a lot of aoe and multi target damage it just seems to run well with him.

Banshee's veil is pretty much self explanatory. good amount of mag res plus the health and mana are always useful. and the passive is great esp if they try to stun you while the shields up.

Randuins omen is useful for the CD reduction (even if it isn't large). But with my inclusion of frozen heart (which is very similar) you could get frozen heart first and get Warmogs or thornmail later. This item is subject to change since frozen heart seems better in my opinion esp if someone on your team has frozen mallet and the warmogs armor and forces of nature combo works so well together. If anyone has anything to say about this please let me know. Note: I would prefer warmogs especially if your not getting forces of nature or have a lack of health and health per 5 as it becomes more useful.

Forces of nature I find to be a great help. It has a large amount of magic res and health per 5 makes this item very viable. This item also stacks incredibly well with warmogs armor. Plus the 8 movement speed is useful since Amumu is fairly slow.

Frozen heart is very important to Amumu for the CD reduction. I don't have much on changing this item out as far as situational items since not much mag res items come with CD reduction but if their team is almost completely full of AP users then Shurelya's Reverie is a good option. I would almost always swap out Randuins omen before I swapped this out for anything else.

Other useful items:

Abyssal scepter would be a fairly viable situational item since it gives AP and an aura for mag reduction. Also since this item has Mag res you wont be at a loss of defensive capabilities.

Guardian Angel is another good situational item since its the only item in the game that gives armor and magic res. The only issue I have with this item is the passive, while I will say that it is very good in some situations in most team fights it doesn't seem to be very effective. It doesnt revive you with a lot of health so its mostly only an item used for escaping and if your team (hopefully not) is mostly dead and their team has 2-3 champs you would just get focused down and you would die fairly quickly. The first time you die while haveing its passive up may get by them w/o notice but once they know you have it they will be waiting to kill you once you have revived. Plus theres a 5 min CD for The passive which is somewhat long. (There are several more cons to its passive as well as pro's but I find other items to be more useful due to their passives. Also this item would probably be much more effective and maybe even a mandatory item in 3v3, but since I play 5v5 I have yet to try this.