Given the incredible damage output you can achieve with Garen's spin with just some AD and crit, i thought that adding some spell vamp to the mix would make him a pretty effecient fighter. This built will crush any squishy champ and make you quite tanky.

Lord Van Damm's Pillager is my personnal favorite item in the game so far, and so, this build will be focusing around that together with the added spell vamp from runes and masteries.

It's a build in progress and i will be checking coments frequently, and edit the guide if anything good shows up. So please comment and rate in order for me to improve the idea.

Pros:

Very tanky early game, and just playing defencively will allow you to remain in lane for ages thanks to his passive.
The added spell vamp will also heal him quite significantly when using his ult, making a tower dive a little easier to survive.
Fighting near minions will give Garen an advantage given that he can also hit the minions with his spin, and thus healing him more.

Cons:

Relies a lot on his spin to do damage and stay alive.
Requires you to know your limits in a fight!