His Passive allows him to stay in the lane even after taking a lot of poke damage/all-in damage from the enemy team. This can also bait the enemy team into wasting a lot of valuable summoner spells.
His E allows him to do more damage in 1 v 1’s (as the damage is increased if the enemy is alone). This lets him do a lot of damage with one complete rotation of his abilities, and unlike Garen, the enemy probably won’t be able to regenerate a lot of health and stay in the lane.
He is really good when flanking the enemy team with his Q and E. Besides that, his W tenacity will allow him to get out of the enemy team if he decides to dive in and disrupt them. Killing him is an ordeal that keeps mounting as the game goes on.
Garen’s lack of CC makes it possible for the enemy to kite him till he falls back or overextends and dies. Since he lacks any form of ranged engagement potential, he is really weak against ranged enemy champions.
He relies on flanking the enemy team from the sidelines. If the enemy team manages to set the proper vision, Garen’s game plan will collapse and he will be useless especially if your team managed to set him behind early on.
Due to him having multiple builds, Garen’s effectiveness can vary from game to game. If he decides to go for the full AD build when his team lacks a frontline, he won’t be able to do anything that game if he is set back. This should be a proper signal for the enemy Jungler/team to camp him when possible.
0 - 15 min
Play safe in the first few levels. Garen needs some time to come online or else he’ll fall behind and be unable to scale.
Once you’ve unlocked your Ultimate R, you can look to play more aggressive. Your Ultimate R can be seen as an execute and will help you finish off the enemy.
Once you have a few levels or an item under your belt, you can look to play more aggressive and look for fights.
15 - 25 min
When no team fights are occurring, split push and draw the enemies attention to you while your team sieges or makes plays on the other side of the map.
Look for picks with your Q and R. Garen deals a surprising amount of damage, so don’t be afraid to move around the map and try to assassinate someone with your team.
Garen is a skirmish heavy laner. When you’re split pushing, look to fight anyone who tries to stop you.
Look for picks with your Q and R in team fights. If you’re able to catch somebody out with the help from your allies, you’ll increase your chances of winning the fight.
Peel for your team as much as possible in team fights. Peeling and keeping them alive for as long as possible will help you win the fight.
If you’ve been harassed and poked down by the enemy, try to retreat and let your Passive kick in. Avoid recalling if possible as the enemy may force a fight while you’re in base.
Garen will gain a huge power spike and finishing ability once he manages to get to level 6. This will let him go for regular short burst trades against his enemies, let his Passive kick in after the trade, and then go for the finish with his Ultimate R after getting the enemy low. In addition, using the lane brushes to conceal Garen's approach will further solidify his position in the lane.
Garen's first item component will either let him survive the lane for a more extended time (tank build) or increase his damage significantly (bruiser build). The former will let him take part in many team fights while the latter will help him with duels.
Garen's build will dictate how he plays the game out. If he goes for the tank build, he will be nearly unkillable and can act as a perfect peel unit for his carries. On the other hand, if he goes for the bruiser build, he will be more dependent on the fog of war to catch enemies off guard and pick vital enemy carries.
At level nine, Garen will have his first ability maxed out. This is a decent power spike as it allows him to duel enemies easily and go for regular short burst trades.
Once he manages to get 2 points in his Ultimate R, he will have an effortless time catching enemies off-guard and killing them. He should use the lane brushes to go for regular short burst trades.
His survivability is outstanding during the mid-game, and he can run enemies down while peeling for his carries. If he takes a lot of damage, he can quickly back off and let his Passive kick in.
Garen will have three points in his Ultimate R at level 16, which will give him a massive damage boost and the luxury to use the ability frequently. Of course, it helps a lot when he manages to catch an enemy off-guard.
His tankiness is overpowered during the late game due to all his items. However, he won't be dying a lot and can easily zone out the enemy from his team, especially if the enemy team has an assassin who likes to dive the allied backline.
Garen will have many items now, which will give him both a damage and survivability boost in the lane. He can tank tower shots for days and allow his team to tower, dive enemies as and when required.