*My First Build, Sorry if I leave any Important Imformation Out*
This build for Annie is the most concrete Annie build you will ever find. Not only does she bring health, she brings a decent amount of ap. Tank Annie is a carry, tank, and still reliable enough to call a nuke. Lets go through the steps to see how to make her all she can.
Laning: You must take mid. The biggest reason being is that you NEED the last hits with your Q ability. If you do not know already, this ability restores mana used if it results in a last hit. Since you take ruby crystal first, it is imperative that you only use your mana to last hit. Until you reach lvl 6, do not worry about wasting your stun. If you hold your stun, you can't farm as much as needed. When hitting lvl 6, flash in, Ult stun, Q, W, Q, ignite. Dead. You will get a kill 95% of the time. Try to recall when you have 1500g or more. This allows you to buy giant's belt, boots, and any wards you will need in your first trip back. Head back mid and keep farming. Always be careful for ganks, as since most annies are hella squishy, you will be a gank target. Not only do you want to be careful for ganks, you want to perform them, gank whenever the enemy team is over-extended.
Mid-Game: You still do not possess the amount of mana that is required to spam, so continue to last hit carefully, and travel with at least one team mate at all times. Since you received mid you do not need to XP ***** as much as the dual laners. You will get focused first and if not second. Use this to your advantage and play aggressive. Fights as Tank Annie are a good thing. You will burn down the enemy faster than they will you. Other mages and carries will be extremely easy to kill, they are stacking ap and ad but not health, unlike you, and are not as durable. Even if they can hit harder, they cannot hit through a Warmogs and RoA. And since Annie hits like a truck with base damage of 300+, you will get the kill before they can. Mid game you will most likely have more health than your tank; so do not be afraid to be the tank. It will be hard for you to die.
End game: You will have 4800+ health. 200+ ap, and enough defenses to keep you in the fight the longest. Carries and other mages will have their final builds done, and this is the time to start stacking some defense. Getting an abyssal sceptor not only gives a huge boost to MR, it also gives nice ap stats. Frozen heart gives you the mana and cd reduction, but also 99 armor that you can't say no to. You are the ultimate tank. You can 1v2, 3, 4, and even 5. You are an initiator, tank, carry, ap, and nuke.
The enemy team will severely underestimate you, and even your own team might think your trolling. Just tell them to be patient and see what's in store. You won't disapoint them.
Note: If you ever over extend and the two opposing members try to gank you, you should start backing. But focus fire one while running away. Remember your stun is your most usable asset, and you want to constintly use it. The enemy champion you focus will get burned down quick (you might even make them back off you), and your stun will keep them off you as well. You have health; don't think that if you get ganked you will die. It is easy to overcome a gank as tank annie.
Note: Annie's stun is the best thing about her. It is what lands you a kill, or lands the enemy champion laughing at you. Always use Tibbers to stun the champion. Not only is it an extremely huge nuke, Tibbers does damage per second to units around him, and being stunned on a unit, will automatically deal damage per second. You can land this stun with any move. Lets say you just used Tibbers 20 seconds ago to escape death, and now a team fight erupts. Use your W skill to stun the enemies now. You want to do that because it is an AoE spell too, meaning many units will get stunned, instead of just one if you used your Q spell.
Helpful Hint: When in base use your W spell and E spell to rank up your charges on your stun. You never know if a team fight will erupt that you have to get too, and it would be much better to have the stun lined up, rather than in the middle of the battle.
But wait, what if you are not doing so good, and the enemy team is extremely coordinated, while your team lacks the ability to know which lane is which. If this happens to you, buy wards, and stay with your team. If keeping your team alive prevents you from some farm.. then so be it. If your build is going slower than you thought, go into the jungle and kill the creeps whenever they are up, it is a good source of gold and they respawn fast. Ask your team for help getting blue, if Tank Annie has blue, she is unstoppable. If you keep your team together then the bad luck should start to turn around. Most people don't want to be the first to die, that's why tanks were invented. If you run in first, the team will follow. Being aggressive makes the enemy team make mistakes. No one expects an Annie to run in, so they all jump in for the kill. Even the ranged carry might push in a little too close, and then your team can come in and wipe them out. Its a sure fire way of pulling the team around, while being the hero.
Don't be afraid to recall. You went mid and got more of an xp advantage than the rest of the team. Going back for something as simple as mana should be done many times. Since you will be last hitting as much as you can with your Q, you will almost always have something to buy too. Even if its just a health pot or ward.
I hope you all have as much success with Tank Annie as I have, and I hope to see some other Tank Annies out there in the Fields Of Justice! :D