I'm not entirely sure what is the best or worst matchups. This is intended to be a mid to late game build. His early game is somewhat weak so you have to play defensively with a decent amount of poke. Just play safe and farm when you can. save your E for engages or disengages and you will be golden.

As stated in the runes notes, I went for the 10% attack speed from runes to start him off in the beginning and following up with armor reds and yellows. Seeing as how most of the damage is going to be coming from his W late game, I put as much into it as possible with AP (normally would have done scaling AP, but he needs a bit of help early).

Attack speed, Attack speed, Attack speed. Tooth is great for the high speed and ability power and the added damage on top. Bork is there for life steal and it's 8% HP damage. These both go very well together for him.

Trinity force is really nice late game when you pitch a boomerang and follow up with all the auto attacks because you can almost 1 shot an ADC.

Get rod of ages fast so you can maximize your E's damage as fast as possible.

YOU NEED YOUR TEAM>>> As much as I would like to say you can carry like crazy at the beginning, it's not so easy. You need your attack speed items and you need all of your abilities as powerful as possible before you can start solo massacring everyone on the enemy team. Hence I say: You need your team. You are the initiate at full rage. bounce on top of them with your transformation E and pound the whole enemy team into the wall. Follow up with a W on all of them and you have pretty much secured victory for your team.