Warwick is a natural monster. With his hard tough skin incoming attacks are mostly reflected and lost health can easily be restored. This is what Warwick is all about! If played correctly he is very sustainable and he can deal a nice portion of damage when he needs to. Especially his instant hard cc Infinite Duress makes him an awesome ganker early mid and late game! Besides that Warwick can both be used for jungling, although he's one of the slowest junglers or as solo top laner. I use this build both for solotop and jungling, although for jungling other masteries will apply.
Go on, give Warwick a try! He is really fun when you master him!

Pros:
-Fast movement speed
-Good survivability
-Easy jungling
-Awesome ganker
-Awesome teamplayer
- Infinite Duress with 40% CDR awesome!

Cons:
-Slow jungler
-Not great damage output late game
-Melee; sometimes hard when laning

Passive: Eternal Thirst
- Each of Warwick's attacks will deal 3 / 3.5 / 4 / 4.5 / 5 / 5.5 / 6 / 6.5 / 7 / 8 / 9 / 10 / 11 / 12 / 13 / 14 / 15 / 16 additional magic damage and heal him for that same amount. Each successive attack against the same target will stack this amount of healing and damage up to a maximum of 3 stacks. The stacks remain for 4 seconds.




Q: Hungering Strike - Takes a bite out of enemy unit and heals Warwick.
Strikes an enemy for the greater value between 75/125/175/225/275 (+1) and 8/11/14/17/20% of the target's maximum Health as magic damage (can only do flat damage to monsters), and heals Warwick for 80% of the damage dealt.

Cost 70/80/90/100/110 Mana
Range 400




W: Hunters Call - Warwick lets out a howl, increasing all nearby friendly champions' Attack Speed for a short time.
Warwick lets out a howl that inspires all nearby allied champions, increasing Warwick's Attack Speed by 40/50/60/70/80% and all nearby friendly champions' Attack Speed by half of that for 10 seconds.

Cost 35 Mana
Range 20




E: Blood Scent- Toggle: Warwick senses enemy champions under 50% life within a 1500 / 2300 / 3100 / 3900 / 4700 distance of him, revealing them until they heal. Upon sensing an enemy, he will gain 20 / 25 / 30 / 35 / 40 % movement speed.




R: Infinite Duress- Warwick lunges at an enemy champion, suppressing the target for 1.8 seconds and striking for 50 / 67 / 84 (+0.4 per bonus attack damage) magic damage in 0.33-second intervals. Warwick gains 30% life steal for the duration, and is considered to have fully stacked Eternal Thirst against the target, which is removed at the end of the duration. Each of his strikes triggers on-hit effects and benefits from life steal and Eternal Thirst.

We start with Hunters Call, since you don't have the mana to use Hungering Strike right away, and you also won't need it so early since you won't be low on health that quickly. This skill is also handy when counter-jungling with your whole team since it does not only increases your attack speed by 40% but that of teammates by 20% on level 1.
Onwards we want to maxout Hungering Strike as soon as possible. It gives you a great damage output both versus enemy champions as for making last hits on minions if necessary. It also helps you sustaining the lane versus ranged enemies, since you will health very fast. However, it costs a lot of mana so use it wisely and buy mana pods if you need them.
Around level 4 your jungler could come by for a possible gank, therefore it is handy to get Eternal Thirst at level 4 to chase down your enemy once they get on low health.
You want to up your Infinite Duress whenever possible since it is your best skill, instant cast with a long CC and pretty short cooldown, it's just great.
Later game we up Blood Scent and Hunters Call about even, since they are both pretty beneficial. With Blood Scent hunting down enemies gets easier and with Hunters Call you'll be able to take towers down quicker and clear minion waves quicker.
For jungling you can use the same skill sequence, but get some more points in Blood Scent since you'll be running around ganking all over the place and won't be pushing many towers.

Recommended

and

Flash is very handy with both escaping enemy ganks as well as surprising your enemies, especially in combination with Infinite Duress your enemy will not realise what just happened!
Ignite is a good summoners spell, even for Warwick. Sometimes it's not viable to tower jump or teammates will come to rescue their teammate. This spell can just guarantee you the kill without risking dieing yourself because of overextending

Other useful spells:
Teleport When solo laning you sometimes want to return quickly for items without your turret taking to much damage. It can also safe you a lot of travel time later game when you are pushing the enemy but want to return for that one item boosting you

Heal Heal can both be a life saver as a surpriser. When your enemies engages on you while you're low health you can both use Heal as Hungering Strike to suddenly heal you for a good portion. Later game heal will get pretty useless since you can regen your health almost instantly by spamming Hungering Strike and with your Eternal Thirst

Ghost Sometimes considered useless on Warwick, but I do think in some cases it is very handy. Your Blood Scent will only trigger on low health enemies. With ghost you can chase down an enemy even on full health and use Infinite Duress to hunt him down.

When jungling, of course take Smite, and secondary I would take Flash.

Offence: 1

Summoner's Wrath 1/1 Only take this mastery if you either have exhaust or ignite

Defense: 22

Resistance 3/3 You want to stack a nice pile of magic resistance also early game
Hardiness 3/3 The same goes for armor, this gives you a nice armor increase especially handy if you face ad champions early game
Durability 4/4 You want a nice amount of extra health since with your items you'll mostly be stacking armor and magic resist. This mastery gives a nice chunk of extra health increasing with you level
Vigor 3/3 Since your Hungering Strike costs a lot of mana you would like to use it as less as possible. This mastery helps you regen your health faster and save mana
Veteran's Scars 1/1 Another nice chunk of health especially handy early game since it does not scale with your level
Indomitable 2/2 Just general good mastery to reduce both incoming champion and minion damage
Initiator 3/3 Very handy mastery to increase your moving speed if you have either recalled for items, are out of position or have to help out teammates
Enlightenment 2/3 Since Warwicks ultimate is really important to him you want to get CDR capped (40% CDR). You items give 35% CDR ( Frozen Heart and Force of Nature). In order to achieve 40% CDR you put 2 points into this mastery
Juggernaut 1/1 Do I need to explain this? Just very good mastery

Utility: 7

Summoner's Insight 1/1 Reduces the cooldown time on your flash
Expanded Mind 3/3 Gives you a nice mana increase, very handy since your Hungering Strike eats mana
Meditation 3/3 helps you maintain mana without using to many mana potions

Since we would like good survivability we opt for magic resistance, health and armor runes.
3x Greater Quintessence of Armor will provide 12.78 additional armor which is a nice boost early game.
9x greater seal of vitality provides a good health increase which will increase with you level and provide 175 additional health on level 18. Not bad at all!
Now we also want to stack a lot of magic resistance so we take 9x Greater Mark of Magic Resist and 9x Greater Glyph of Magic Resist providing an additional 22,14 magic resistance
I take a bit more magic resistance than armor since our items later in the game provide more armor than magic resistance. If you want you can even the armor and magic resistance out by replacing some Greater Mark of Magic Resist by some Greater Mark of Armor

If you want some more damage output you can also opt for more AD in trade of some health and/or magic resistance and armor.
In that case take 9x Greater Mark of Attack Damage and 3x Greater Quintessence of Attack Damage
which provides you with 15.3 flat AD which is awesome for early game ganks!

Runes which are acceptable for Warwick

Magic Penetration Since Warwick damage output is for a large part magical this provides a slightly better damage output which is always handy
Magic Resist As before, beter survivability versus AP champions
Attack Speed Better damage output as well as last hitting minions
Armor Same reason as magic resist
Attack Damage Makes it easier to last hit minions, also bigger general damage output
Health Don't need to explain this I guess

Which runes should not be picked at any time

Flat Mana: You get enough out of items, masteries etc.
Mana Regen: Same as above
Cooldown Reduction: You get already capped with masteries/items
Ability Power: Early game useful, later game you just don't do enough damage to make it useful
Energy Regen: You use mana, no energy, totally useless
Critical Strike: You don't have any critical strike items nor AD so useless
Armor Penetration: You don't have a great damage output so not useful.
Lifesteal: You have your passive + Hungering Strike + wriggle's lantarn, you don't need more
Spellvamp: You don't have enough ap to make this useful and you have enough life steal already
Reduced Time Spent Dead: If you work on not dieing in the first place... ;)
Experience: You better not die by skipping these runes, makes you gain more xp than these runes

Core:

When winning:

Here we arrive at the so called "core" of the guide, the items
Solotop you kind of want the same items as if you're jungling, only maybe a little bit more defensive. We'll start off with a Long Sword to ensure we easily get the last hits. When jungling the Long Sword is also useful since it helps you get through the jungle fast.
You can take an optional Health Potion if you think you need one, but remember that yourr Hungering Strike health much health as well as your passive. Maybe a Mana Potion is handier. When jungling you don't really need any of the two.
Next you want to get your Wriggle's Lantern really quickly, just before or after your Boots. After wriggle's finish your set of boots. If you're facing someone in your lane AP or the team is AP heavy get Mercury's Treads and if the team is AD heavy get ninja's tabi
Now depending on if your team is winning and if you're facing AD or AP enemy champions and whether you have a major mana issue you either get a Glacial Shroud that will later build into your Frozen Heart or go for Wit's End if you're confident and/or need the extra magical resistance. After this you usually finish your Frozen Heart which gives you a nice CDR, armor and mana. If your team is already winning however (because you made some awesome jungle ganks or your team is just good) you can get a Malady straight away. You still have a nice armor and magic resist while your output damage is majorly increased. To finish the game quickly get a Black Cleaver, but if the game appears to be dragging on go for the Force of Nature instead. Many will argue why you should better go for the Banshee's Veil and why it is better, but believe me, it is not better!
The Force of Nature provides a lot more magic resistance, as well as a nice movement speed and health regeneration. You already have a nice manapool from your Frozen Heart and without any additional health items the health boost from banchee's veil is also not really big.
Getting into the late game you have to decide whether your team lacks damage output or sustain (usually you lack on of both in a normal game ;)). If you need more damage output go for the Madred's Bloodrazor and for Black Cleaver. If your team needs more a support (off)tank get the Shurelya's Battlesong. It will give you a good health boost, cap your CDR on 40% and the active can save your teammates life or give your team the essential kills they neem late game to end the game. Finishing off with a guandian angel will ensure that they will not quickly focus you and with your 40% CDR on Hungering Strike and major armor and magic resist you'll be unable to be killed, but on the counterfeit will not have a major damage output.

Some of this guide is my own experience and investigation, some of the things I used were explained by others. I would like to thank:

-jhoijhoi, for the "how to make a guide" guide found here
-Muukzor, for helping me improve the guide!
-SuperLemrick, for poiting the guide of jhoijhoi out =D
-Mobafire itself for the warwick skill information
-Anyone who reads this guide and comments, both positive comments as remarks!

I hope you enjoyed it, go kick some *** wit Warwick! =)