Efficient early lane trades and kill secure with [R].
Durability and crowd control
Every 4s your next attack on a champion deals bonus damage, heals you, and permanently increases your health.
Increase your Tenacity and Slow Resistance for each summoner spell on cooldown. Immediately after casting a Summoner Spell, gain a larger burst of Tenacity and Slow Resistance for a moderate duration.
After 10 minutes gain 8 Armor and 8 Magic Resist and increase your total Armor and Magic Resist by 5%.
Restore health over time based on your missing health.
+65 health and +9% attack speed
Takedowns on enemies grant permanent Tenacity.
Deal 7% more damage to low health champions. Gain AD/AP after kills or assists.
Unfortunately Garen doesn't have any fantastic keystone choices, Grasp is just the best of the bad.
You should be able to proc Grasp relatively easily in melee matchups with [Q] and the bonus max health synergizes well with your [W].
The bonus tenacity and slow resistance will help you overcome Garen's biggest pitfall of getting kited by CC and slows.
With Unflinching you should be able to stick to your target for the kill much more easily.
Conditioning allows you to scale into the mid game as a very threatening tank.
Strong AD Matchups: If playing into a strong AD matchup like Renekton or Camille, take Iron Skin.
Strong AP Matchups: If playing into a strong AP matchup like Rumble, take Mirror Shell.
Second Wind synergizes incredibly well with Doran's shield and Garen's passive, allowing you to take numerous early trades and regen substantially.
Legend Tenacity allows you to stick to your target so that you'r able to continuously pumping out damage to your opponent.
Coup De Grace's execution nature synergizes very well with the execution damage pattern of Garen's [R], securing kills that may otherwise not be possible.