Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
I'm not so good playing League of Legend, but I love this champion and I widely played it. I wrote this guide, cause I think I found a manner to play Gnar more and more effective than builds I found over the internet, so I want to share with You my experience. Just consider that, actually, I'm on level 22, so I really don't know what will appen to level 30 (considering more skilled player but even full masteries and runes).
Anyway, after played with Poppy and then returned to Gnar, I found It a little more squishy than I had remembered so I asked myself: "What if I set It on Resolve and buy more tanky items?" Things went better but, in early game, I usually die too many times and my opponent gets stronger than me so, one day, I asked myself: "What if I buy tanky items before attack items?" So the magic happened: my opponent didn't expect I was so bulky and I became literally unmovable (gaining more levels than my opponent), sometimes I could even resist (running away of curse) to 2v1 or 3v1 ganks.
Moreover I found that the ability to remain in combat is really funny, especially with a champion like Gnar. You can surprise your enemy remaining in close combat, doing a lot of damage with your Hiper and, when they finally think they can get rid of You, transform into Mega Gnar, to get more HP and finish them!
Some things to keep in mind
1- Mobility is important, You sacrifice your attack power for extra-defense so make sure You can reach your enemies or run away from them if things would go wrong; after-all this build is intended to play safe (and, possibly, relaxed);
2- If you have to deal with an AP champion buy Spirit Visage first or ask someone to change lane to face and AD;
3- Mortal Reminder is situational, consider that I've never played in late game, sometimes this item (that I like very much) could be useful to You in mid game. I found It very strong against champions bulkier than me! :)
1- You do a lot ot damage with Hiper on every third hit on a single target and you boomerang will stack, so use it to hit multiple enemies and finish them with basic attack! Or maybe with the boomerang too!!! It's so exiting... Isn't It? :D
2- Don't remember to scream loudly while playing, everyone in your house (and/or in your Skype Chat) have to know You are proudly playing GNAAAAAR!!!