This is NOT a warwick jungling build but simply a great build to kill your enemys, and to carry your team! Warwick clearly is a great jungler but as your may already know but this build focuses on mostly on damage ,armor penetration, and attack speed. This is a unique setup since his ultimate is based on how much attack damage he has (Warwick quickly strikes the target 5 times for 33% of his attack damage plus 40/60/80.).

Armor penetration is a great tactic for Warwick becuase it can shread through enemy tanks and make it much easier for Warwick to kill them.
Now, if your facing tanks or theres fed tank that just doesn't die, then The Black Cleaver is a great option. Since The Black Cleavers passive is not UNIQUE that means you can stack the affect so its not a bad idea to get maybe 2.

NOTE- If the enemy team has a bunch of stuns, slows, taunts, fears, snares, sleeps, and/or immobilizes then i really suggest you get mercury treads, they are really helpful to escape or catch up easlier

I chose Wits end because it is great for casters, it is great for making mage champions useless against you or any other players. Warwicks ultimate strickes 5 time for so each time so he strikes that leaves the opponent with 210 less mana.

Mastery's
I choose to go 21/0/9 because there are many Damage advantages like- Havoc (increases your base magic damage and base damage by 5%)
or-sunder (your physical attacks ignore 2/4/6 of the targets armor, witch is better considering damage is what this build focuses on.

Summoner ability's
I choosebecuase it is good to help out your team to catch up to a opponent or to simply help yourself escape a single enemy.
I choosebecause it is good to finish off a enemy with low health. If your ultimate is still on cool down and your opponent is real low on health it is a great technique to finish them off. Also in team ganks on single enemy's it is good to use it at the beginning of the fight because it reduces incoming healing by 50% so if the single enemy has heal only 50% regains.

Story

-Warwick counted himself amongst the most powerful and revered men in his home city-state of Zaun. Over the course of his infamous career as an alchemist, Warwick won many honors for his craft, not the least of which was a lucrative offer for service in the Noxian military during their campaigns against Ionia. Sequestered in his labs far from the front lines, Warwick and his apprentice Singed toiled relentlessly to manufacture all manner of appalling concoctions for the Noxian army. So potent was his art that even the greatest of Ionia's healers - under the leadership of the Starchild Soraka - struggled to combat the poisons and chemical weapons generated by his despicable mind. Warwick's reign of terror grew so horrific that his very name became a curse in the eyes of his Ionian foes, and they began referring to him only as ''the Deathmaker.''

But even one under the protection of the Noxian High Command is not wholly beyond the reach of retribution. For as Soraka strode across the myriad of death and destruction left in the wake of one of Warwick's chemical attacks, her heart finally gave way. She called down the wrath of the cosmos on Warwick, wishing that his form should mirror the cruelty in his heart - a curse that would come at the price of her aspiring divinity. Within his laboratory, a terrible thirst took hold over Warwick. As his apprentice looked on in horror, Warwick threw open the doors to his bastion and sprinted off towards parts unknown, a bloodcurdling howling marking his passage. He had become a werewolf; a wild, murderous beast. Today, the Blood Hunter fights for Noxus within the League of Legends... thankful of the curse that his now-mortal enemy bestowed upon him.

''The rage of the beast now compliments his predatory spirit.'' -- Singed, the Mad Chemist, upon witnessing his master's transformation

Abilities

First ability

Hungering Strike - Takes a bite out of enemy unit for damage 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 (can only do flat damage to monsters), and heals Warwick for 100% of the damage dealt.
Cost
60/70/80/90/100 Mana
Range
400

Second ability

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. This increases 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
35/35/35/35/35 Mana
Range
20

Third ability

Blood Scent - Warwick passively senses weakened enemy champions around him. The scent of blood sends him into a fury causing him to move at incredible speeds.
Toggle: Warwick senses enemy champions under 50% life within 1500/2300/3100/3900/4700 distance of him; while he detects a low-health enemy, he gains 20/25/30/35/40% Movement Speed.
Cost
No Cost
Range
20

Ultimate (Fourth ability)

Infinite Duress - Warwick lunges at an enemy Champion, suppressing his target and dealing damage for a few seconds.
Warwick lunges at an enemy Champion, suppressing his target for 1.7 seconds. While they are suppressed, Warwick quickly strikes the target 5 times for 33% of his attack damage plus 40/60/80. Warwick gains an additional 30% lifesteal while performing Infinite Duress.
Cost
100/125/150 Mana
Range
700

Passive

Eternal Thirst - Each of Warwick's attacks will heal him for 5/10/15 health. Each successive attack against the same target will restore increasing amounts of health to Warwick.

Tips

Warwick is a champion particularly well-suited for killing monsters in the forest. Hungering Strike can sustain your health, especially if you are able to get the Anicent Golem's blue buff.

Warwick's ultimate can stack on-hit effects such as the Black Cleaver or Madred's Bloodrazor.

I appreciate anyones feedback or comments-negative or positive, thank you.