Garen'shealth regeneration is greatly increased due to his passive, Perseverance. This only activates if he can avoid receiving champion damage for 9 seconds, granting him exceptional sustainability in lane, and minions don't stop his regen.
盖伦的Decisive Strike makes him a powerful chaser, easily closing the gap and silencing enemies before they can cast a slow or any debuff. It can also be used to make a swift escape since removes slows.
Garen can be lethal in early game fights, especially after getting his ultimate. Judgment deals good continuous damage to enemies. Decisive Strike's speed boost is good for chasing enemies. Demacian Justice also does extra damage based on how much health the enemy has missing
Garen's best starting skill is Decisive Strike, as it can be used to last-hit, silence, speed himself up, remove slows, reset autoattacks and has very high burst damage at early levels.
Courage and Decisive Strike mix well for a powerful chasing, and escape combo. The speed boost from Decisive Strike letting you get into, or out of range, while the damage reduction of Courage allows you to take reduced damage from nearby minions and enemies when chasing or escaping.
Unlike other abilities, Judgment remains active when Garen is stunned because it is not a channeled spell.
With some points into Judgment, Garen can easily farm and push minions with it.
Judgment is Garen's main source of damage, but has a significant cooldown and long duration to maximize its damage. Make sure you activate Judgment properly or you will be left being fairly ineffectual in combat while it cooldowns.
A common rune page for Garen is going for total armor penetration build. With maxed Quintessences and Marks, will deal good damage on early game allowing for a quick first blood in a duo lane or using Exhaust , as his lane phase is strongly dependent on his ability to hit enemy champs with 盖伦的Judgment and 盖伦的Decisive Strike.
Garen damage output is very high early game; avoid early confrontations.
Harass Garen in lane every few seconds, if possible, to minimize the effect of Perseverance.
Ranged champions can easily stop Perseverance with an autoattack (unless Garen goes farther back, which has him give up last-hits) and farm in lane while a safe distance from him - they generally also have abilities to let them keep away from Garen even if he charges at them. Ranged carries in particular will scale far stronger than Garen in this situation, avoiding his early-game advantages while securing their own late-game advantages.
Avoid going into a brush that does not have a ward in it if Garen's current whereabouts are unknown. Garen players have a tendency to hide in bushes, due to the synergy between his silence from Decisive Strike and damage from Judgment.
Garen is a cooldown based champion. However, all of his ability cooldowns are very high. Try to attack him when they are on cooldown.
It is often worth the investment to purchase armor to counter Garen's high physical damage.
Like most melee champions, Garen is quite vulnerable to ranged harassment.
But because of his really high damage and the fact that most ranged champs are squishy, at lvl 6 he can burst them down instantly. So if the ranged champ doesn't get a good advantage over him, he will melt anyway.