This build is Very good and i play This build all time. Anivia is Good Middle Player. Sorry for my English, because i learning English =)

Marks: Best marks is on Magic pene, Because you deal Better damage Throught Magic Resist.
Seal: Best marks is on Ability power.. 6x 0.59 AP and 2x 0.1 AP per level.. at level 6 you have Very much AP on mid
Glyphs: Same as Seals.. 6x 0.99 AP and 2x 0.17 Per Level
Quintessence: Best is Quintessence on AP... +4.95 AP (10 AP isnt Very much, But In mid you can Have Nice First blood

Rebirth: Passive spell. This spell Revive you, after 6 Seconds When you die. Cooldown Has 4 Minutes Cooldown and cant Reducted thsi cooldown. If you stay Nearby turret, You cant die with this passive. If Anyone Gang you on mid, You use to Turret Range and you Transform to Egg and cant die

Flash Frost: Basic anivia spell.. You must Cast this spellat enemy, If Flash Frost trought enemy, you must Destroy Him behind target

Frostbite: If Enemy is Stunned/Chilled with Flash Frost, You must cast Frostbite. It deals Double damage to CHILLED Champions. You may Cast Frostbite after , too... Because Glacial Storm (ULTIMATE) Apply CHILLED STATE on enemy.

Crystallize: Its skill to Team Fights and you Dont Need it on lower level. YOu must Maxing Frostbite. This Crystallize Wall yooucast behind enemy, if Enemy trying Get out of Team fight. After Wall you cast Flash Frost to Stun enemy, Glacial Storm for Slow enemy and then Frostbite for Deal Double Damage.

Glacial Storm: Your ultimate skill. If enemy is nearby of you and you havent Flash Frost, Glacial Storm is your Best Choise. You slow enemy and Take double Damage with Frostbite. Then you Can Use Frostbite and Again cast Frostbite. This si Massive combo and Can Kill enemy.

Flash: Flash is Best Summoner spell on anivia. you can left from all Fights.. Anivia has Stun,Slow,Crystal wall and if you have flash , They cant kill you.

Clarity: Clarity is good spells For Newbies. If Anivia hasn't mana, you can use clarity, But for kills is better Ignite.

Ignite: Ignite si Very good spell on anivia. Its help you for First blood and Versus lefting enemies

First you must Have level 6 (With level 6 its Easilly)
1. First use skill Flash Frost to stun enemy.

2. Use Frostbite to Take DOuble Damage to Enemy .. If you are good, Enemy can have -50% HP

3. go nearby at enemy and use Glacial Storm and then Frostbite to Take Double damage again.. if Enemy still Alive, Use Flash to Teleport nearby enemy and Cast Ignite For kill him..

I Doing this every time and enemy cant kill me. i have First kill on Middle Every time!