Hello, and welcome to my second build here on mobafire! This time, it's for anivia, the first champion I ever tried to play well! I recently decided to buy her, and finally start playing her again, which I did today, I played a very bad first game, but my third one was a flawless game where I got 8 kills I believe. I did that without any build, so I decided to develop a build for her, aiming to win in either 3v3 or 5v5, seeing as I'm better at 3v3, while Anivia is best at 5v5.

Pros and Cons of Anivia, the Cryophoenix.

Pros:
-Very potent harasser
-Very strong early game if you know what you're doing.
-She can wall off enemy escape routes with Crystallize
-She got a lot of CC
-Anivia is very durable during the game due to her passive.
-Being able to nuke enemy champions.

Cons:
-She is really slow.
-Vulnerable to CC
-Squishy.
-Like all casters, if not farming correctly, will be weak late game.
-Her spell combo is aimed towards hitting your Q, which is a skill shot.
-You must know when to time Crystallize.

There are some more subtle pros and cons, but these are the most noticable ones.

Laning phase:
Anivia is able to dominate every lane. Every single one. she can duo lane effectively. But where she excels at, is solo laning. Her Q ability has enough range to be shot from behind your minions toward the enemy minions, so it's really hard to zone her out of the lane. I personally haven't had any problems against anyone yet, just tanks and Malzahar specifically are the ones I have problems with. Why? Mlzahar has his Q, which silences, and his E is annoying, since it passes on to another unit when it kills the previous one.
During the lane phase, I try to stay in the lane long enough to buy the archangel's staff in one go when I return. To achieve this, you must be A) Harassing a lot. B) Not taking so much damage. C) Not spamming skills so you don't waste all your mana. D) Last hitting well. Also, when you are laning, and your opponent is close enough to land a spell combo, make sure he pays for it. It's YOUR lane, he isn't in the position to do anything. Make him go away by all means necessary. Each time he has to go back for mana / health, you have a couple of seconds to farm.
While farming, try not to use your ultimate as much as you can, it drains mana like crazy. You can go from a full pool to a almost empty one in a matter of seconds. Leaving it on for a second or two is fine, but don't let it drain your mana, because you need to have enough mana to harass.

Early Game:
-Try to last hit as much as possible (Will be covered later.)
-Try to harass opposing champion(s) out of the lane.
-Try not to recall until you have enough gold to buy your Archangel's Staff.

Midgame:
Your domination has (hopefully) begun! Now it's time to start ganking and or killing your opposing laner.

Killing with anivia:
This may be a bit late, but I'll do it anyway. Killing with anivia is easy once you get your Archangel's Staff. Your combo would look something like:
Flash frost, pop for stun, Wall enemy off, use ultimate, Frostbite, Ignite. If you get a kill, well done, if not, Harass for a bit and then try again.
A quick note about Frostbite, Frostbite deals double damage when the enemy has been slowed (the ice effect provided by Ashe, Nunu and Frozen Mallet). But that doesn't mean finishing off nonfrozen enemies with frostbite is bad. I'm not saying you should killsteal. But you are a caster, and casters are hungry, hungry for Gold. AP is very expensive.

Late game:
Anivia is a very potent initiater. She can wall off a single enemy champion so your team can jump on him and finish him in a few seconds. If nobody is commiting to a teamfight, you can bait enemies if your passive is off cooldown, by charging in (not too far so you get killed of course) and kite em into your team.
If you kill 2 or 3 enemy champions, immediately push a tower, seeing as Anivia can wall off incoming, respawned enemies, giving you and your team a few seconds longer to push a tower or inhibitor.

Skills:

Flash Frost:
I make Anivia sound really easy in this guide (atleast, I think so.). But in reality she's everything except easy. She has two skills that I will be explaining here. The other two are pretty self-explanatory.
First is Flash Frost. It's your first spell in your spell combo. When you fire it, you can press Q anywhere down its trajectory to make it pop. When it pops, all enemy champions in a small radius of it get stunned and frozen. This is all good and dandy, but hitting the initial projectile and stunning is a lot harder than it sounds. Sure you may hit it a few times, but you want to hit every single one of them. To do that, you must (successfully) predict your enemies' movements. Try to predict what they will do before firing Flash Frost at them.

Crystallize:
This skill is AWESOMEness in the form of a wall. This skill is a gamechanging skill in the hands of a skilled player. But, when in the hands of a less skilled player, it can change a win, into a loss. (For example, trapping a teammate.).
It's also a good initiating skill like I described before. Master this skill and all it's different uses as quickly as possible, or you will be nothing but an average nuke. There are so many things you can do with this.
-Wall off escape routes
-Wall off chasers to get away.
-Facecheck bushes.
-Wall of enemies so they have to take a route you planned.
-Initiate a teamfight.
-Hold off incoming champions to kill someone or destroy a tower.
-Scout ahead.
With all those options, might wanna make use of em. So use this appropiately, and it will make you win games.

Optional items:
There are so many situational items Anivia can buy. When the game drags on longer, and then I mean long, as in you got all your items already and got lots of excess gold, make sure you get 5 Archangel's Staffs and A rabbadon's deathcap. That means you get the maximum AP you can get.

Items you can get before the game lasts that long are Banshee's Veil, which is good against anti-AP champions like Veigar.
Mejai's Soulstealer is good when you get a lot of kills early on.
Ionian Boots of Lucidity are good if you don't need Magic Penetration, and would like a bit of cooldown reduction.
Void Staff if your enemies are stacking Magic Resist.
Abyssal scepter when you need magic resist. (Veigar could be a reason.)

Last hitting:
Last hitting as Anivia is HARD. Due to a long attacking animation and low damage on her autoattacks. However, it is extremely important that you are able to last hit consistently, seeing as you gotta get your items ASAP.
For those who are new to the concept of last hitting, here's a breakdown:
Last hitting means you do not just randomly attack minions, but that you let the minions fight, and kill the minions that are low on health. This results in you getting more gold, but less pushing the lane. When your opponent isn't last hitting at all or very badly, you will overpower him in a matter of time. But he will push harder. While last hitting is easy to do, it's hard to master with Anivia, due to EXTREMELY low early game damage (Around 60), so you gotta get that down.

I hope this helps you at least a bit in mastering Anivia, the Cryonphoenix! Give me some feedback on how this build could be improved, or things I didn't explain yet!