PROS

-Heavy early game pressure
-Great at controlling the map
-Fast clear speed
-Good at securing objectives


CONS

-No AOE damage (ult is quite unreliable)
-You're forced to ban Vayne every game
-People might think you're trolling
-Requires good jungle knowledge

This past preseason, Nunu has been consistently at the bottom of the w/r charts with a 33% w/r in the support role and 45% in the jungle in Plat+ elo.

However, I think this is not due to the champion being weak, but because people don't know how to play and build Nunu correctly. My build may seem absurd, but give it a try and you'll see that it is insanely effective.

The problem all along was that Nunu wasn't capitalizing on his perma-slow effects. Nunu basically has a built in frozen mallet, and if you look at all the champs who build frozen mallet, they ALL have on-hit builds.

MONSTER CLAPPER NUNU takes advantage of this built-in effect and utilizes his perma-slow with his E and the attack speed/movespeed buffs with his W. Along with his natural bulkiness, MONSTER CLAPPER NUNU will be a force to be reckoned with, inciting terror in both the enemy jungler and his camps.

Press the Attack The only mastery you should get. You're building on-hit items, and using this would only amplify it even more along with your W.

Overheal You can use your Q to overheal you. You'll be sacrificing some bulk to build the on-hit items, so this would be a little helpful.

OR

Triumph This is another great option. If you feel like you'll fight a lot, this is a perfectly fine choice.

Legend: Alacrity Self Explanatory. You want more attack-speed. Never take the other options.

Coup de Grace IMO this isn't a good mastery, but the other two options are even worse, so you'll have to go with this.

Cheap Shot This mastery is amazing. It will make up a good portion of your damage, and you could activate nearly every time it's off cooldown. THIS MASTERY IS REQUIRED.

Relentless Hunter This lets you roam around the map more, and could help you finish of targets by running them down.

Ninja Tabi This item is overpowered. You should almost ALWAYS get this item.

Mercury's Treads The only time I will ever buy this is when the enemy AP damage is extremely fed early on.

Skirmisher's Sabre - Bloodrazor This item is what makes this build unique, and what enables Nunu to do what he does. It makes Nunu a capable duelist and have quick clearing speed.

Sunfire Aegis This item is also required. It makes your clear speed even faster, and the damage from the cape is great since you stick onto your target very well. Great item overall for Nunu.

Blade of the Ruined King Makes you an even stronger duelist. However, I wouldn't recommend getting this as your fourth item (after boots, bloodrazor, and sunfire cape) unless you are fed. This is a great fifth item though.

Thornmail No explanation needed here. Great for making you a lot tankier.

Spirit Visage Lets you heal more from your Q, and the CDR is nice. Get this if there is AP threat.

Wit's End I actually find myself building this more often than Blade of the Ruined King. It will boost your E damage too because it lowers the enemy's MR, and should provide a damage similar to that of BotRK.

You would want to start with a point in Q, of course, and W next for better initial clearing speed (I've tested this out).

Unlike most other Nunu players, you will max E first with this build. With Skirmisher's Sabre - Bloodrazor you don't need Q to clear camps anymore. I usually put another point in Q at level 7 though for more sustain, but you would want to max E first. Remember, you can only counter-jungle if you can either:
1) Kill the opposing jungler if he comes.
2) Have vision on enemy jungler and you know you can safely take their camps.

With Nunu's high base damage on E, option 1 can easily be accomplished, and even if you can't fight them, you can definitely just run away.

Don't try doing early dragon though, you won't have enough damage/sustain until around level 7.

The playstyle with this build/setup shouldn't be any different to other builds. Only now, you are actually a threat and you're capable of actually killing people.

Also, you might've noticed that this is called MONSTER CLAPPER NUNU, and it's called that because you will be able to take down the jungle extremely fast. With your natural bulk from Q stacks and overheal, there should be no champion who could 1v1 you.

Your early game should begin with Blue/Red -> Wolves -> Red/Blue. After that, look for a gank. If all the lanes are shoved, ward for your team and try counterjungling a bit. If there's nothing to take, just go back to farming your jungle. You will be able to clear faster than the enemy.

This build is strong for the very same reasons as to why Shyvana is a top-tier jungler right now. They both clear quickly, they both are great duelists, and the only difference is Nunu has far better ganks but Shyvana has better teamfighting potential due to her AOE. However, games are decided by early game nowadays, so Nunu would be a better pick if you could press your lead, especially along with the fact that you could HARD PUNISH the enemy at 20 minutes with an easy Nunu cheese.