This is the build I've developed from frequent Spirit Breaker play. It's been working well for me ( 80% win rate ) so I thought I'd share it!

It's a fairly aggressive build and has some risk early game depending on who you're laned against, due to only having one salve. But it generally works out very well, as you'll start with 872HP and 74 Attack. It will make last hitting very easy from lvl1 and harassing hurt like a b*tch.

Be ready to start charging by or before lvl3 if enemies in any lane are low on health
(if you're going to another lane, back out of your lane a bit so that you don't charge past wards or alert the enemies you're charging, or else it could screw everything up.)
With this build, you should often be able to even get first blood in your lane, very early, if you have a good support/nuker/disabler with you.