Your mana scales with AP mate :P thats the problem.

That reminds me....I remember a Kat who took lol

I prefer building this on him to handle the mana problem but still be usefull:

-> This will help you with your mana costs and the ap scales REALLY good with his kit. see above This is what actually gives you your mana back, because as we all know, garen has a mana regenation of -5 (up to -15) per 5 seconds. The cdr is great for your W, since this is your main damage source. This is needed to have a reliable mana income from Essence Reaver, otherwhise you won't crit often enough. The extended range also helps A LOT. Your worst enemies are your teammates, this will help you if they decide to group up with you. You need this to find the enemies which are most likely hiding from you.

IF YOU ACCIDENTALLY HIT E PLEASE REMAIN CALM AND FOLLOW THESE STEPS:

1. Press enter
2. Drink some Mountain Dew
3. Leave the game
4. Uninstall LOL
5. Turn off your computer
6. Throw your computer at your neighbour and scream: "DEMACIA"
7. Now spin to the nearest bridge
8. Climb over the edge
9. Drink bleach

i use to play ap garen with Deathfire Grasp and sorc shoes