There are many options for building champs. Instead of listing all others in an attempt to cover all bases. Just read other peoples builds. There are many other builds that work and are able to work in different roles. Simply put if you are solo queing rank games. And for some reason after you locked Alistar and told your teamates what you were doing they still decide to pick 4 tanks you need to realize there are many options. I agree for a premade 5 man there are other options. But to be clear those are all highly Dependant on the 4 guys you play with. my point is this may not be perfect for every team but it works.
With that in mind i humbly show the strength that is Roaming AP Alistar.
note: I am aware i have poor writing skills. play me some time... this works. Bamazar
Introduction to Roaming as Alistar
Now the first thing to discuss is what roaming is. The concept of roaming if often unknown to new players because of its counter-intuitive plan. The basic idea is your team will succeed if you keep yourself under-farmed. The Centeral Idea is to keep all your lanes at the half way point. When you get to the Half way point leave your lane. Plain and simple. Go to one of the other lanes. If all 3 lanes are past mid go to the jungle. If you have a jungler go to the other jungle. If there is a team fight be there. If there is a empty lane cover it and let the jungler focus on the jungle and the ganks. Your job essentially is to be the manager of your team. You stand back and make sure they do their jobs. The main thing you should purchase is Wards, just like a manager puts cameras up at work, you need to as well. If you don't know where all 5 enemies are you find them with wards. This is the method of play during the laneing phase. Alistar is an amazing champion for roaming because his skills are the main portion of his success. He does not need items he does not need experience (compared to other champions). All Alistar needs to do is Flash---> Pulverize---> Headbutt--->Unbreakable Will--->Victory. Carries need to max AD in order to do their jobs, Mages their AP. Alistar needs map awareness and team awareness. Neither of these things are achieved by farming Minions. Just get him his Lucky Knife, his boots and Philosophers stone, he will level fine and have plenty of gold from assists and kills from all the ganks you'll be doing. Simply put Alistar doesn't need to farm; He's a cow hes been on a farm his whole life and he's sick of it.
AP Alistar vs Tank
Lets discuss a Tanks job. Start the fight, protect the carries and survive. With unbreakable will you will survive Period. People dont want to hit Alistar to begin with. They are gonna attack the Ashe, Stun the Viegar, and snare the TF. No one wants to focus the tank. Most people are of the camp at the start as no one wants to focus Alistar. This allows this bull to pass out headbutts like its going out of style. If they do decide to attack you, Unbreakable will will be ready to cast with all the cooldown reduction. You will survive. You will be the tank and not back down. Your powerful heals will save your team mates, your skills will kill the carries. The Basic combo of Pulverise - Lich Auto- Headbut-lich Auto deals over 2k damage in 4 seconds. You will kill it. You are still the tank, but a tank that cannot be ignored.
The runes are pretty straight forward. Magic Pen Runes for all your attacks and passive, while the MP5 and Cooldown reduction allow you to maximize the effectiveness of your passive. The speed quints are to maximize your roaming potential.
The cooldown reduction on your spells and on flash are the best notes of this build. With Unbreakable will being ready for every team fight. IMO the benefits of the defensive tree are simply not enough to counter balance the benefits of this build. You will be spamming spells and not even feel it in the mana department.
Items create death combo
The key thing to note here is buy wards. Buy them all the time. You need Lucky Knife, mobility boots and the stone ASAP. the reason you get these early is because it will be what compensates you during the roaming stages on your gold gain. After that its key to rush Lichbane as fast as possible. after every spell Alistar can get an auto attack off (including headbutt). This causes with his AP being around 500 by games end and and auto attack of 120. the damage stacks fast. Flash, which triggers Lich, for an auto attack of 600, Pulverise for 600, Lich for 600, Headbutt for 800, Lich for 600. The entire time your passive is dealing 100 damage per second. this leads to your basic Combo doing 4k to one target. I rounded the bulk of these numbers because with resistances a lot of it will vary,in addition with the cool down on lich timing is key, but it give you a clear demonstration of his raw power. With unbreakable will and dealing 4k single target. You can be a tank and the carry.
Flash is almost a requirement for Alistar. Which causes the next spell to be highly up to debate. I personally use teleport for this reason
Often junglers run in a predictable path. The key part is the red lizard buff is an important part of a junglers path for 2 reasons.
1. He is facing his hardest jungle fight (often lowest in health).
2. This is often his last stop before he goes back to to shop and then he will be typing to discuss ganks. This means he is often with less items then he will be in 30 seconds, when he is fully buffed and ready to gank.
Typically a good jungler will be at this part when you as a laner are at level 4. So the basic plan is to place a ward you buy at the start next to the red buff. As soon as you see him at the buff. you go back to base and teleport to him and wait in the bushes.
Its important to note that you have more options here then you'd think.
1. Kill him after the fight is done. If he is very low on health let him kill the lizard and then tear his head off this will make sure he has all his spells on CD and the Lizard did the max damage to him that was possible.
2. Fight him While the lizard lives. This plan is if you dont think you can kill him. Many WW in mid game can just fight him at full health the entire fight. In addition to this are exellent solo champs so fighting him after he gets the buff is just silly. So the plan here is to scare him off for a bit. Basically it will make him be underfarmed and no one gets the buff. As stated earlier Alistar doesnt care about items and farming. Junglers do, doing this is a victory you just messed up his day and his ganks.
3. Last Hit the Lizard. This plan only works against weak junglers. Often bad junglers use Smite as an opener or as soon as it comes off CD. This is dumb and they deserve to learn its dumb. Because a ward is there (and you also) You should be watching for when he cast Smite. if he did at the start I highly recommend making him pay for his error. With the new patch Update you can target minions with headbutt, as a result you can headbutt the lizard steal the buff then stuff the silly Udyr who thought he had a good plan. Note after you steal the buff there is a tough call. Kill the jungler or run like hell. remember both are good plans and both are highly situational. I will mention with the lizard buff you will be a force he may just run from you. The point is you will be deep in enemy territory with two lanes full of champs around you. You basically need to be able to kill him in 5 seconds or run , other wise you are going to die when they come to assist and then you pass the red buff to one of his allies. And to be clear that is much worse when you stole the red buff from a level 4 WW but gave it to a level 6 Ashe. You died and you sentenced your mid lane carry to death as well.
The other two options I will give for summoner spells are Ghost and Clairvoyance.
Ghost because it adds to your mobility for going lane to lane and clairvoyance because it lets you track the enemy. I personally feel wards and shurelya's make those two options less valuable but i can see that they have their merits.
I will mention this is my first build on here and I look forward for feed back on structure of the guide and I can add sections if needed. I am very aware i didn't include a lot of options for variation from my build. I could write down every item in the game to try and make sure I get a high rating to avoid down-votes. but whats the point of writing a guide if the conclusion is "ignore everything I wrote and figure it out yourself". This build works and yes some items may get switched out for more defensive alternatives, to find out what items are more defensive go read a tank build. Yes other things work. and Yes Ive thought of any other item that has AP and some other stat. They also work fine and I encourage you using them.
The Main point
Buy Lucky Knife , Philosopher stone, mobility boots and Lichbane. After that just win the damn game.
June 14th 2011.
Updated Item List: Void Staff replaced with Abysmal scepter to add move team synergy and MR reasons.
Updated Item list: Philosopher stone replaced with Archangel because of Unique passive gold per 5