This build I just discovered while trying Volibear and he is now my main xD.
I am currently on a 16 win streak and have had most kills in almost every match.
Good luck. :)

I choose flat HP quints for that starting durability and armor and magic resist per level seals and glyphs to avoid having to buy resistances late game.

You'll probably see these items and think "wtf n00b" but they work.

The berserkers greaves and phantom dancer give you incredible attack speed once you have 3 stacks on Frenzy, which synergizes very well with your ulti in team fights or tough 1v1s.

The frozen mallet is so you can just keep slashing at Teemo while not sacrificing too much by not getting another warmogs.

The warmogs and atma's are because you are volibear and they are 100% essential. With this much HP, atma's will give you DPS rivalling a melee carry.

Basically, you start off with >850 HP and start killing minions. Preferably, don't lane with a support in this case unless they can dish out enough damage too. Just wait till the two enemies try to kill you and your team mate and beat the s##t out of them, you should have the health to, throw them, then slow them if they try to run, then bite them when they get to <15% health and you should have a kill. Keep doing this and you will get fed to buy these items, then you win. :) You can now 1v2 anyone and sometimes 1v3 and you are a great help to your team with your throw/slow, assuming you aren't taking every kill (you should take most).

A short guide but meant just for the build, comment if it works out. :D