Anivia is an incredibly scary late game caster who can deal a ton of damage over time. However, Anivia can make a surprisingly great tanky ap champion. Anivia has one of the highest base armors in the game, and her passive essentially grants her a second life. These two factors, coupled with guardian angel, allows Anivia to NEVER, EVER die and increase her presence in teamfights.

This is a game that I recently played with my tank Anivia build. My other games are similar in which I never die and stack kills and assists. This build is legit. It works.

Pros:

• You will never die, 100% guaranteed.
• You still do okay damage despite not building much ap because Anivia has good ap ratios.
• Great utility (2 aoe slows, 1 stun, 1 bigass wall)

Cons:

• You don't do as much damage as boring ap Anivia.
• You might get raged at for building stuff differently and not being a mindless sheep.

I run magic penetration marks, greater seal of vitalityhealth per level seals, flat magic resist glyphs, and movement speed quintessences.

The seals, glyphs, and quintessences are self-explanatory since Anivia has low base health, magic resist, and movement speed. Other solid alternatives are flat armor seals, ap/level seals, flat cooldown reduction glyphs, magic resist/level glyphs, ap/level glyphs, flat health quintessences, and flat ap quintessences.

The choice of marks between magic penetration and ability power is a little more subtle. Basically, if you are going against someone in mid with no scaling magic resistance and who probably is not runing for magic resist (such as Annie), then run magic penetration marks and get sorceror's shoes to obtain 29 magic penetration so that you basically deal true damage. (Since you are going tank, I would advise switching back to mercury's treads after laning phase, but it's up to you). Otherwise, flat ap marks are better.

Update: I run 21/0/9. Full Offensive AP masteries and pick up meditation under utility because Anivia's very mana intensive.

I run 0/9/21. Anivia needs those 21 points in utility, especially in Meditation, Quickness, and Intelligence. With my build I get a ton of mana so Strength of Spirit in the defensive tree synergizes extremely well.

You could also run 9/0/21 and pick up Archaic Knowledge for the magic penetration.

Flash is obvious because of its utility in positioning walls and landing q + ult -> e.
I run ignite because it is imperative for early game burst for securing kills and late game for forcing a carry out of a fight. (I'd honestly rather run revive for the lols but i'd get chewed out every game. See below for my thoughts on revive).

Good alternatives are exhaust, ghost, and teleport.

I see clarity a lot, but that can honestly be remedied with good mana management. It doesn't scale very well late game either, which is when Anivia needs mana more if she can't get blue buff 24/7.

If you want to troll (by troll I mean do something new and completely different, but viable), you can run revive. Although you will rarely die with tank items + egg + guardian angel, you still might anyways due to stupidity/bad teammates/something that was your fault. Then you can run revive so that whenever you DO die, you can get revenge kills or defend. since the cooldown will have ran out by the time you died again (Getting the revive mastery is imperative in this case).

I run QEEWER -> R>E>W>Q
-> > > >

Q is a one point wonder. It is a skill shot and it moves really, really slow. It will rarely hit, so it is not a good idea to place more than one point in this skill. However, if it does hit, then coupled with E, Anivia may be able to win her lane outright. REMEMBER TO DETONATE IT JUST AFTER IT PASSES THROUGH AN ENEMY CHAMPION TO DEAL DOUBLE DAMAGE AND STUN THEM.

W is one the best utility spells in the game. It is what separates good Anivia players from the bad. A well placed wall can delay bad team fights by preventing the enemy from initiating, disrupt team fights by splitting apart the enemy team or preventing them from escaping from aoe damage. A poorly placed wall can mean the death of your team. (Note: Please do not intentionally troll with your wall.) You definitely want this maxed, but since E and R are Anivia's main sources of damage you want to max those first.

E is your bread and butter skill. It is Anivia's main nuke, but prior to level 6 it can only deal respectable damage when Q hits; however, E is so potent when coupled with her ult that it must be maxed first.

R is an amazing skill. It is an aoe damage over time spell that slows attack speed and movement for 20%. Because it chills the enemy, Anivia will deal full damage with E. Max this ASAP, it is Anivia's main source of damage and provides a great deal of utility

I get sapphire crystal + 2pot first for the early mana and the ehp of the health pots. ( Boots + 3pot is also acceptable in lanes that can more easily dodge q or run out of range of e).

After that, I rush a catalyst the protectorcatalyst, followed by a tear of the goddess. You will likely not be hogging blue buff, so you NEED the mana and mp5 asap. Follow up with an archangel's staff.

Choice of boots are self explanatory. I prefer mercury's treads because it helps Anivia's low magic resist, but if you are against a Tryndamere or a Master Yi you probably want Ninja Tabi to get some lucky dodge procs. Other choices are Sorcerer's Shoes for the magic penetration (essential if running magic penetration marks and Boots of Swiftness for positioning (Anivia is really, really slow).

From there, build tanky. GET GUARDIAN ANGEL FIRST. You can rarely afford to have your egg pop in teamfights because it greatly decreases your overall survivability and the risks you can take.

If at any time you need quick armor, get a glacial shroud.

Complete your catalyst with a banshee's veil, and follow up with an abyssal scepter do you don't fall behind in damage output. Finish off with a frozen heart.

OTHER GOOD CHOICES:
Sunfire Cape is boss (el oh el doing damage while still in egg form)
Randuin's Omen is great since you want health + cooldown reduction. Also you build so much resists that the active is extremely potent.
Force of Nature provides much needed movement speed, magic resist, and lots of health regen
Get Warmog's if you really want health or if you are getting Force of Nature, because both items synergize well with their health regeneration.
Quicksilver is a highly underrated item. Enemy Mordekaiser, Malzahar, or Warwick? NP, get the sash and pop in when they use their ultimate on you. /trollface
or Snowball items are great because you never die. If you are losing stacks on these, then something is wrong.
Shurelya's Reverie is extremely underrated. Sick regens, builds from a philosopher's stone gp10 item, and provides a huge team wide ghost for initiating/escaping.
Rod of Ages provides health and mana to synergize with archangel's, as well as provides decent ap. Just make sure to get it early so that it can charge up.
Athene's Unholy Grail gives nice mana regen, magic resist, and a good amount of ap.

Solo lane, no exceptions. Do not dual lane because you may be forced to be more aggressive than you have to and you will just get less farm. Do not jungle because you will either die (very bad) or never finish (also bad).

Play passively pre-6. Only throw out a Q if you think you can hit the enemy(or throw out a Q for mindgames/keeping them on your toes) since your Q will rarely hit. If you hit with your Q, only then do you follow up with E.

Of course, if you find out that your opponent is completely brain dead and manages to not dodge your Q at all, then of course you can be more aggressive.

When you hit level 6 and get your ult, try to force the other person out of lane. With your ult you should be able to hit an E when they are chilled every time.

You want to have an archangel's staff by the time teamfights start breaking out. You need the mp5 and the sheer amount of mana from it in order to sustain your ult.

BE AGGRESSIVE. You have egg, you (hopefully) have guardian angel, you have a ton of armor and magic resist. You can afford to make silly plays and tower dive and in general play more dynamically than usually because you are surprisingly one of the tankiest characters in the game.

Split push like a boss. You can clear minion waves extremely fast. You can tank tower hits extremely well. If the other team goes after you, then have your allies attack another tower because it will probably take them an hour to pop through guardian angel + egg (and if you have revive, then all their efforts will be in vain).

This is, after all, a team game. So we need to consider synergy when selecting our champions.
Note: this is not an exhaustive list and will probably never be an exhaustive list. This is not something that you can really effectively list for someone else's benefit; it just comes with experience and game sense. This just provides a general scope of what works with Anivia.

Ashe and nunu are very good partners with Anivia. They have abilities that can chill opponents so that Anivia can do double damage when using her E. Additionally, the combined slowing effect is extremely synergetic for a kiting compostion.

Zilean and Yorick can use their ultimates on Anivia to really, really anger the other team. This leads to funny results when the other team has to kill Anivia 4 times.

Anyone with a stun, snare, slow, or basically anyone who can initiate( Maokai and Malphite are very good examples)is good so that Anivia can land her ult -> e -> q -> e combo more efficiently

Playing Anivia as a tank is a very different and interesting (read: hilarious) style of playing her. Try tank Anivia out, it's a lot of fun when you never die.

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08/26/11 -- Updated masteries. Uses awareness in lieu of expanded mind
08/17/11 -- Made the guide look pretty. Updated rune analysis, optional items, and other miscellaneous things
08/16/11 -- Hotfixed skill chart
08/16/11 -- Uploaded Guide