Sorry, I don't have the patience nor the time to write a guide for now, but I thought I would share this Twitch build. It's the way I build him, and although it's rather expensive, it can REALLY carry. The life steal combined with extremely high critical chance is absolutely deadly to the enemy team, especially with Spray and Pray active. At level 18 as the build comes to fruition, I can easily solo Baron with my auto-attack (ending with full health, even) and turn the tide of the game in my team's favor.

However, keep in mind that this build is EXTREMELY susceptible to crowd control. Don't initiate fights if you're playing against champs with lots of CC. The only exception to this is 1v1 situations. For instance, if you cross paths with Fiddle, he can fear and drain you. By the time this is done, he's got full health and you've got half or below. However, this ridiculous damage and life steal completely overpowers his drain and you can finish him off easily, ending with full health. This build can also tank towers by itself if the enemy's minions are close by. Hit the turret a few times, life steal the minions, and repeat until it's down.

If you play Twitch, feel free to leave a comment giving me some recommendations. I don't know everything about this game nor do I pretend to, and would love any advice you all could share.