Here are some pros and cons with this Garen build:

PROS:

- INSANE early game damage
- You can take down turrets 5 times faster.
- Feels A LOT stronger in teamfights
- You get to be both a damage dealer and VERY tanky
- It's fun to watch someone get Oneshot in a second

CONS:

- Squishy early game
- Risky build path if your whole team is losing
- Many people can start spam pinging your items thinking that you're trolling.

I will try to explain as briefly as possible why I have picked those runes:



Combined with Sheen, it's amazing. And since you're essentially a tank, it deals increasingly more damage. Also stacks hp with every proc which is amazing for you since you are squishier early game.

Does that even need an explanation?

Works very weill with your passive and if you start dorans shield.

Again, getting free hp.




tiumph It can be the difference between living and dying, especially if you like to tower dive. Try to keep your W for after the kill if possible to buy yourself some time for the heal after the kill to come.

Simple: works amazing with your ult, which is an execute based on missing HP.

To make this build successful, you need to become a monster in the early game. To do that, you need to start by winning your lane HARD. How? It's easy. If you are not getting engaged by your opponent, only trade with him (Q into E and maybe an auto attack here and there) when you have your Grasp of the Undying is ready.

If you're going with the Sheen build, you can trade without having Grasp of the Undying but for the optimal damage, you would want to combine both.

If you are dominating your lane really hard, make sure to keep pressuring it, because you might as well be able to 1v2 if you have Trinity Force completed and going for Stormrazor. If you see that sometimes your opponent can outdamage you, just start roaming around and snowball.

A lot of people question the Zzrot portal as a choice of an item, but it is simply AMAZING when it comes to split pushing especially if you get Trinity Force as well. It works great with Black Cleaver too. Make sure to ALWAYS coordinate your push with your team and tell them to go for either Baron or Dragon (depending on which lane you're pushing hard)!

If you exit the lane with Tabi, Bramble vest and Sunfire, you are basically unkillable. Try to use that as your advantage if you team desperately needs you in a teamfight. Make sure to use W in the right moment to avoid a long CC or a huge burst of damage!

If you go for the Trinity Force build, keep in mind that you might be a bit squisher so try to play the teamfight clever! Always go for the most squishy enemy first since you can easily delete them with just 1 combo of Q > E > AA > Ignite > R.

For a conclusion I can say that I find this build to be extremely fun to play even if it's on a very mainstream and "no skill" champion, but after you see how much damage you can do on lane and in the late game and how funny it is to OS people within a second, you might start liking it too.
If you have any questions or if you just want to see first hand how that build works, you can join me on my stream. I'm live every day from Monday to Friday.
Now go spread some JUSTICE on the rift ;)