So, this is the first build I have ever created, so feedback is very much appreciated. I'll try to be as in-depth as possible here without being too lenghty.

Nunu is one of those champions that is good at basically anything. He is one of the most effective laners in the game and is one of the easiest junglers. I won't go into detail about this here though, more on that later.

Pros:

• One of the best harassers and damage dealers in the game
• Hard to take down because of your high amount of health, armor and magic resist
• Ultimate with possibly the highest amount of damage in the game
• You can heal a great amount of damage with your Consume skill, allowing you to stay in your lane longer
• Give yourself and your allies increased attack and movement speed with your Blood Boil spell
• Passive that allows you to cast a free spell after every 7 attacks

Cons:

• Because of your high amount of damage you get focused a lot
• You may have mana problems early game
• If you're against a team with 3 or more cc'ers it will be very hard to use your ultimate effectively, because every stun, snare, taunt, silence etc. will cancel it
• Easy to escape your ultimate if your enemies have or aren't in the center

- A great passive and essential early game if you want to harass properly.

- This spell is what makes you such an effective laner and jungler. You never have to go back to heal and you can keep harassing and damaging your enemies while you just keep healing back any damage done by them. This is also why you don't need to buy any health potions and go straight for Rod of Ages. Use this spell whenever you can, even when full health, to gain more minion kills aswell. You can also use this spell on Tibbers, Heimerdinger's turrets and Teemo's mushrooms!

- This is your build in Ghost spell with bonus attack speed. Pop this whenever you need to escape or chase an enemy down. Note that you can use this spell on an ally champion so the both of you get this boost, without halving the effects! Use this wisely and keep this spell on your team's damage dealer at all time (yes, the cooldown is shorter then the duration, so you are literally able to keep this spell up permamently).

- Your main damaging skill. This and your spell make you a feared enemy early game. This spell does 85 / 130 / 175 / 225 / 275 damage + 100% of your ability power and even slows your target's movement by 40 / 45 / 50 / 55 / 60% and attack speed by 25%. What else do you want? Spamming this spell without thinking will get you out of mana in no time, but if you keep your Blood Boil on you will be able to land 7 hits on minions a seconds or two after this spell has recharged, meaning that you can basically keep firing this spell for free during the laning phase.

- This is what makes you a feared opponent. In every single teamfight you will be the center of all enemy focus because of this spell, and everyone will want to have you dead before you can cast this successfully. Channelling for this spell takes 3 seconds, so make sure to time it right. Using your Flash spell and then hitting your target with an Ice Blast before channelling will increase your chances of succeeding. Be aware that every single stun, snare, taunt, silence, etc. will cancel your this. Especially champions such as Sion and Malzahar will be a real pain for you. A good counter to this could be Banshee's Veil, or simply make your team focus the enemy cc before casting this. If you are up against more then 1 cc, you'll want to cast this while you're in a brush. When you are in a brush channelling, your enemies won't be able to notice what you are about to do! Use this to your advantage and surprise your enemies!

- Personally I'm not a fan of this spell, mainly because the recharge time is very high and it's easy for your enemy to catch up to you if they pop , but this spell is a must for Nunu. Whenever you use your ult, people will always try to get out of there as soon as they can, so Flash is a great spell to get your target at the center of your spell to make it harder for them to escape it. They won't even be safe right beside their own turrets anymore. Ofcourse, it can also be used as an escape mechanism, but try to save it for a combo with your ult.

- I always take this spell second for Nunu. Your ult is often the key in winning a team fight, so you always have to make sure you are there. It's also useful during the laning phase and your teammates or enemies are initiating in a different lane. You can teleport over there at any time, right into the center of your enemies, pop your ult, and kill them all.

- Speaks for itself. Ofcourse, this should only be used when you are jungling.


If you don't like either of these spells though, these 2 spells also aren't bad possibilities:

- Another great spell, but not the spell to take for Nunu. Both your Ice Blast and Absolute Zero spells got slowing effects, so this spell is also unnecessary. If you still want that extra slow, however, replace this for Teleport.

- A personal favorite, but not the best choice for Nunu. In all honesty, this still isn't a bad spell to take, but since you already got your Blood Boil and should keep that up as much as you can, it is kind of unnecessary. If you still want that extra boost, however, replace this spell for Teleport. Could also be replaced for Flash, but is far less affective because you won't be able to surprise them anymore.


You should stay away from the other spells though.

- I often see Nunus with this spell, but that is completely unnecessary. You already do plenty of damage with your spells, and the other already mentioned spells are way more effective for you. Let your carry take this.

- You will often get focused by Sion, Taric and other cc'ers, so Cleanse would be a great counter. If your enemy is smart, however, they will save it for when you use your Absolute Zero, which makes this spell useless for you.

- You should be harassing and helping your teammates throughout the entire game, so you don't need this spell, and you don't need the damage bonus either. Let your support or tank take this.

- Bad idea for you. Let your support take this.

- Might be useful for you early game because you may have mana problems, but if you make good use of your passive this shouldn't be necessary. This will become completely useless late game if you make good use of buffs.

- You already have your Consume spell.

- Might be funny to take if you want to get first blood, but otherwise useless.

- Please just don't.

Games should start with you buying Doran's Ring to allow you keep using Consume and Blood Boil whenever necessary. Those who don't like this item could go for a Meki's Pendant Meki's Pendant or Boots of Speed first though. If you are jungling, go for a Cloth Armor and 3 health potions first. Remember you don't need to buy health potions when you are laning!

The first time you go back you should buy a Catalyst the Protector Catalyst the Protector and Boots of Speed if you hadn't done so in the start, or go straight for Rod of Ages, which will be your core item alongside Void Staff, which you will get at your next return after completing your boots into Ionian Boots of Lucidity. We go for Rod of Ages because of the high amount of ability power and the health and mana bonusses. By the time we have this item we will have shown them how fearful Nunu can be, and they will be stacking magic resist. Which is why we get Void Staff, what gives is a good amount of ability power and 40% magic penetration.


The next items we get will be depending on the situation

Morello's Evil Tome
This is a great item that gives us a good amount of ability power, mana regeneration and cooldown reduction, which is all that Nunu needs.

Guardian Angel
A good amount of armor and magic resist with a great passive, which could also be used to your advantage.

Zhonya's Hourglass
Good amount of ability power and armor with a great active. Again, use this to your advantage.

Abyssal Scepter
Good amount of ability power and magic resist, good passive.

Rabadon's Deathcap
Gives you a ton of ability power. Get this instead of Zhonya's Hourglass or Abyssal Scepter when you have no trouble surviving.


Items not to get:

Sorcerer's Shoes
Some people like to use these boots for Nunu instead of Ionian Boots of Lucidity. While there is nothing wrong with that, I personally prefer to use Ionian Boots of Lucidity because your Void Staff will already give you all the magic penetration you need, thus the cooldown reduction from Ionian Boots of Lucidity will be much more useful and needed.

Banshee's Veil
Some people like to get this item for Nunu to protect his Absolute Zero spell, while that is actually useless. If the enemy team has something at least resembling a brain, they will cast a different spell on you before casting your cc spell to stop your channelling, making this item completely useless for that. If the enemy team only has 1 cc'er, simply let your team focus him before casting your Absolute Zero, and if your enemy has more then 1 cc'er you should be in the bushes waiting to ambush from there or surprise them with your Flash spell. We already got the hp and mana from our Rod of Ages and the magic resist from our Guardian Angel and Abyssal Scepter.

Rylai's Crystal Scepter
Not a bad choice, but I prefer over this because of the extra health and mana boosts. It's passive is great, but since we can already slow our enemies with our Ice Blast spell this is unnecessary.

Mejai's Soulstealer
A great item to stack ability power and cooldown reduction when you have 20 stacks, but also a tricky item since you will get focused a lot. This item is only recommended when you know your way around Nunu and should be completed after Catalyst the Protector Catalyst the Protector.

Nunu is basically able to go anywhere he want. He could go to a side lane, take mid lane or jungle. The place where Nunu is the most effective though, is in a side lane. Nunu isn't the most effective farmer in the game, so if you got an Ashe or Caitlyn on your team you should always let him take the mid lane. What you are best at is harassing and keeping your enemies from farming, which is why we go mid. If your team doesn't have a jungler, you could do this aswell. If you do have a jungler, you should go to a solo side lane. You'll be able to farm more effectively that way and even start to push 2 enemies back on your own soon enough. Simply keep harassing with your Ice Blast spell while healing back any damage done with your Consume spell and try to keep Blood Boil on as much as possible so you can get the best out of your passive.

When the laning phase is over and you have hit level 11 and got your second rank in your Absolute Zero and have maxed your Ice Blast spells you should focus on keeping the enemy carry from farming and pushing to destroy turrets, putting your Teleport spell to good use. Tell your team to make good use of wards so you can teleport there aswell.

During late you should always stick with your team. From now on your Absolute Zero spell will be essential to winning team fights, so you need to make sure you will always be there. Make sure to keep your Blood Boil on your team's carry at all times and harass the enemy with your Ice Blast spell.

Start with a Cloth Armor and 3 health potions and go straight to golem. Use Consume and the moment is spawns, use a health potion and then finish him off with Consume when it has recharged. Because Consume has high cooldown this will be tricky, which is why we get Greater Seal of Resilience and Greater Glyph of Focus runes when we are jungling instead of Greater Seal of Potency and Greater Glyph of Celerity runes when we are laning to give us the extra armor and flat cooldown reduction we need. You should be level 2 now and pick Blood Boil. Go for wolves now, and go for the wraiths after that. You should be level 3 now and pick your second rank in Consume. From now on you should make your priority and start ganking while jungling now.

After testing this and other builds extensively I can say without a doubt that this is the most effective build for Nunu. This gives you a ton of ability power and health early and mid game while focusing more on survivability late game to keep you alive in ganks.

I will try to answer all questions, suggestions and comments to further improve this guide.