This is my first guid, so it may look sloppy, but that does not mean the guide is bad. This build is for a more aggressive graggy early which carries over to late game

I choose Flash and ignite due to the fact that I tend to be a more offensive player, and with gragas, the flash helps for placing your ult behind enemies, as well as escaping those sticky situations. As for ignite, I just got used to using this skill on my other champs, so I pretty much carry it with any one that I play as a carry that lacks a DoT. I highly recommend Flash as one of them, but the secondary is up to you.

As I mentioned in the previous chapter, I play Gragas as an AP carry, therefore my rune set up like alot of AP carries has magic pen Marks, and flat AP glyphs and Quints. The seals I found best for Graggy were the HP per lvl due to the fact that, late game it gives him some better survivability, as well as makes mre use of his passive. But I can still see using seals of Clarity and/or Replenishment due to the fact that he is a rather mana hungry champ even with his Drunken Rage.

My skill sequence is set to give you alot of damage out-put, as well as some sustain in lane with leveling your Drunken Rage. I find that using his charge early game is kind of a waste of mana unless trying to initiate and or position yourself for an ulty or barrel roll. I also find it more of an escape mechanism early game which i why I leave it at level 1 till I've maxed everything else. Once I grab a Lich bane though, I tend to use this move as a chase due to the fact that it slows, and does nice damage with all the AP you've built up.

The masteries are pretty much self-explanatory, more AP=more damage, and utility is mostly for keeping your mana up while giving you that little extra movement speed to catch your enemies off guard.