This is my first build on here so any suggestions fixing small mistakes would be appreciated.

The primary purpose of this build is mainly to throw your enemies off, they will see you doing massive damage with your basic attacks and decide to stack armor. But when really the majority of your damage output is going to be from your items magic on-hit effects.

The second most important part is that it maximizes the damage from your ult with each little baby hit applying on hit affects.

Pros:
mad crazy attack speed, which works very well with your passive lifesteal
very hard-hitting ult
pretty tanky
good jungler

Cons:
more item dependent than most AD builds
pretty weak mid-early game
requires lots of farming
no boobs =/

AND THIS BUILD IS VERY SITUATIONAL.
this build is meant to shred tanks and you're much better off going straight damage and attack speed if the other team is very squishy.

Honestly i wasn't too sure about the runes, i figured armor pen and health would help alot with early jungling and faster movement and reduced cooldowns are just nice to have.

I like smite to help me take down the blue at level one, although it is possible to jungle him without smite, hes ****in' warwick after all. And exhaust is great for ganking. But of course the summoner spells are never set in stone

Same goes for the masteries, i like the less time spent dead and increased buff length, and the offensive masteries help with early jungling.

I prefer hunters call at level one over hungering strike, but they both do a good job of helping you kill the blue at level 1.

Afterwards maxing hungering strike first gives you good burst damage at lower levels, maxing blood scent second really helps your ganking strength allowing you to chase anybody down. although its usually a good idea to keep it toggled off until you charge in, as the icon above peoples heads tends to scare them away.

Of course get madreds bloodrazor forst like you would using any warwick build.
depending on how well you're doing farming and ganking you may even consider finishing the whole item before you buy boots, it comes down to personal preference and the situation of the match.

Sword of the divine, and wits end, both give fantastic attack speed, and along with madreds, give you a metric ****-ton of magic damage with each attack, and jacks the damage of infinite duress waaaayyyy up. Taking even champs with 4000+hp down to about half hp with one skill.

|||||||||*****!!!!!|||||||||

And the sunfire cape gives you awesome survivability, and a little bit more magic damage.

As for the 6th item, games will rarely last long enough to get this, but it is purely situational.
Some suggestions are:
Frozen Mallet- nice slow and even more hp
Phanton Dancer- ****ing cool name "I wanna go fast!"
Rhabbadons Deathcap- you're owning the other team and just feel like ****ing with them
Malady- Even more attack speed and magic damage

And remember, this build, and any other build on the internet, is rarely to be copied exactly, depending on the flow of the game, the item sequence, and even item choice, will have to change to best suit the situation of the match.

Any feedback would be appreciated
Enjoy!