50% of garen's damage early game comes from his Q the rest from his E. This build basically furthers that concept of the Q being his burst as well as not sacrificing Overall survivability.

This build is off the concept that tank plank is running where his parlay does the damage and from then on it is tank plank for a few seconds. But i believe garen could do it better.

Trinity Force - This proc plus Q = 600 damage nuke late game. as well as a chance to slow.

Sunfire Cape - 35 damage per second accents his E very well. as well as giving life and armor.

Atma's Impaler - 2% of max hp as damage is a minor bonus as well as armor and crit chance which up his survivability and spin damage. Yes spin can crit.

Infinity Edge - Best garen item ever, but not always wise. Use with caution. You will notice a huge ammount of burst in his damage, but offers nothing to survivability.

Last Whisper - 40% armor pen is very good for those armor stackers trying to counter your awesome. But for a while ur fine with just brutalizer.

Boots of Swiftness - only other option is merc treads.

Flash - A must. Charge Q flash to em Hit spin Dead.

Exhaust / ignite - Summoners preference. Ignite secures kills so you dont have to dive, Exhaust offers late game survivability and an early game slow since they cannot hurt u while ur spin to winning.

Try It understand it. Main it, Garen isn't just a beginning game character with these builds.