is probably easiest and possibly most powerfull natural jungle of League of Legends. He also can be played on lane, but most players play him as jungler. Why? Check out next chapter !

Pros:
+Fast and easy jungle
+Natural lifesteal
+Very good ganger
+His Hungering Strike take % health
+Attack speed buff for him and allies next to him ( very good for pushing )
+Very usefull ult - Infinite Durres

Cons:
-Hard to gang untill lvl 6
-Ult can be canceled

Marks:
Greater Mark of Attack Speed - faster jungle, bad late
Greater Mark of Desolation - universal

Seals:
Greater Seal of Health - you loose less life at jungle, you are more tanky. Best choise for [Warwick]

Glyphs:
Greater Glyph of Magic Resist - Warwick must be very tanky. That's why m.res glyphs

Quins:
Greater Quintessence of Desolation - same as marks - universal ( good jungle, good dmg )
Greater Quintessence of Attack Speed - very fast jungle, not the best late game

Why 16-5-9?

16 in Offence will give you more dmg on jungle and normal fights
5 in Deffence will give you more ressistances. You'll be more tanky
9 in Utillity for more exp, healh / mana regen and [Ghost] upgrade

Madred's Bloodrazor - great item for [Warwick]. On his ult each attack activate on-hit effects like 4 % health from madreds or 42 magic dmg from [Wit's End]. Madreds give armor as well.
Wit's End - One of the best items for Ww. Same like up + gives us m.res.
Spirit Visage - 15 % more healing and regenrating - just great. With his ult and passive it do his work great. + give some survive
Sunfire Aegis - armor health + when he uses his ult he deal 35 more dmg per sec. It works very well on him.
Guardian Angel - nothing to explain.

Other great options:

- Wriggle's Lattern - good item for junglers. You can buy it instead of [Madred's Bloodrazors]
- Banshee's Veil
- Malady
- Randuin's Omen

The best options are OR OR

+

Why?
- good to chasing or just running away from danger.
- great for ganging especially to lvl 6. Good for helping your teammates as well.
- flash flash flash.. nothing to explain
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My favourite and probably most effective jungling route for ww :

Enjoy !

is great champion for new players. With him they can learn how to jungle, what is jungle role in game. He can jungle without any runes as few in lol.

I hope my guild helped you to know warwick or his build and you'll enjoy it !!

If you see any mistake write it on comments !

Cheers