This is my first build here on Mobafire, but I've played this permanently for half a year now and i found out that this build is the best for a Pure AP Nunu. Then you will have one of the best damage in the whole game.

Now you might think he is extremely squishy, but because of his tanky Q skill (CONSUME) and the OP passive (One free skill use (only Q or E) which will cost NO MANA). But it's also very important that you repeatedly take blue buff so you can spam you snowball, heal and remember the awesome cooldown reduction ;) At end game you will get about 4,3 sec cooldown on the snow ball and that also means that the enemies WONT escape! And.. you will hit 3000 if with 20 stacks of mejai's.

I use Flash and Teleport, because i find it very helpful with Tele to save towers and get some easy ganks/kills. Flash is also a very efficient skill to use in order to land your Absolute Zero ultimate.

This full AP rune build is extremely efficient to get your very wanted first blood. In lvl 1 you will hit 140 only because of the runes. Now you can also have 5 Magic pen Marks, which will give you a very good hit too.

In team fights you can try to spam the snowball at the most squishy enemy target as much as u possibly can without being hit. If your level is low and you haven't got Frozen heart and archangel staff you will need to have blue buff to spam the Q or else you mana will drop very quick and when the team fight is at it highest you wont be able to flash in and ult.

Buy amplifying tome and a mana potion. Be quick so that the enemies wont get to your brush before you do. Learn the Q and wait until the enemies enter your brush. When they enter you want to use your Q and slow them down. Focus them and try to get as many snowball hits as you can.

DOMINATE THE LANE!

LvL 1 to 6:
In early game its very important to get control of the lane and basic hit the creeps so that you can use your passive. When your passive is enabled you will get a blue ring around you. And this way you will spam your snowaball (Q) without using any mana and harassing your enemies extremely well. Now remember that you can also use your passive at the E skill to heal if they manage to harass you. But i mainly prefer to use my "free spells" at the Q because the heal needs less mana than the snowball.

LvL 6 to 11:
Now its time for insane damage. You will hit 230 with your snowball and 680 with the ultimate. But it is important to wait in brush until u know the enemies will enter(they wont see ult unless they see Nunu himself). Then begin loading your ultimate and as soon as its finished your opponents should have Very little Hp even if they are a tank. So just spam your Q. Now if you have last a big amount of health heal yourself on a creep and keep on spamming the Q. I normally don't focus on getting minion kills but rather lowing the enemy, but also make sure to get as many minion kills as possible even though you are focusing on harassing.
Nunu is very good to solo dragon so if you are handling the lane well you might wanna take dragon for you and your team mates. Also go mid and try to get a kill sometimes if the enemies stick to their own lane. I normally don't go back until lvl 6 - 8 but be careful when u finally do so and don't use your teleport unless you need it for helping the tower or lane mate, because if they manage to push the wave and take much hp of the tower. -Towers is one of the most important things to have in a game so guard well.

When you go back to purchase you want to buy Mejai's soulstealer and sorcerer shoes. If you have enough money buy one of the items of the void staff. Void staff is the most important item so be sure to get it as fast as possible.

In mid game you want to gank with your team mates and keep killing the dragon as often as u can. And most important is to have blue buff.

Im not finished with the mid game and endgame, but i will work on this build sooner or later. Please rate