This build may look strange to the naked eye, but bear with me and I shall show you how my ideal Galio is played. As the title says, this is a 'Pew Pew' build, meant for outlaning your opponents with SUPERIOR FIREPOWER. Both the range and damage on Resolute Smite/ Righteous Gust are great for doling out constant harass while keeping the summoner moderately safe. The items above are the 'ideal' items; this is if your game is going 'piss easy' and you feel that almost no early game tanking on your part is needed. But at the same time notice I did add a Force of Nature and Sunfire Aegis just for people to consider them as options. Anyway, read on for a build that is quite off the beaten track, and fun as hell to play.
SIDE NOTE: I'm not new to Mobafire, I have just never bothered to make any prior builds. BUT..... I can show you guys how to kick ***, and as long as that's what you're here for, then you won't be dissapointed.

(pros) - Amazing farmer (clearing creep waves in seconds at level 5)
- Great Laner
- Lots of harass ( Resolute Smite + Righteous Gust )
- able to keep distance
- can close gaps fast (slow and MS boost)
- one of the best Tanky dps in the game ( Bulwark + Idol of Durand )
- Can solo a lane with ease
- Can also mid
- Lots of nukes early game
- Is extremely suited to destroying Casters ( Runic Skin )
(cons) - is (sometimes)countered by Melee dps champions in a fight ( Highlander, Ragnarok, Xin Zhao)
- Some ranged Dps champs can tango better than you Lay Waste, Acid Hunter, Tristana, Twisted Fate, Sanguine Pool.
- Have to wait for your cd's (which are not very long but still)
- Mana problems unless Tear of the Goddess is quickly acquired

Greater Mark of Magic Penetration - Standard on any Magic Dmg champion
Greater Seal of Scaling Mana Regeneration - Combined with a meki pendant at lvl 1, you can always have enough mana to spam abilities
Greater Glyph of Scaling Cooldown Reduction - gives almost 9% cd by lvl 18 and so these are quite viable to have. Especially with this build, late game I don't buy any cd reduction items
Greater Quintessence of Health - My early game preference (combined with Veteren's Scars)

Other choices for runes, persay if you don' have these ones (though I recommend the above runes) are:
- Greater Mark of Magic Penetration
- Greater Seal of Evasion
- Greater Glyph of Magic Resist
- Greater Quintessence of Magic Penetration

For masteries I like to go 9/21/0
Offensive Tree - To achieve Archaic Knowledge for that extra 15% magic penetration which synergizes with all Galio's offensive abilities.

Defensive Tree - So I can have Veteran's Scars (more health) as well as Strenght of Spirit and Tenacity (this is a Tanky AP build may I remind everyone)

Now.... About Strength of Spirit... Before you downvote, I'll have you know that it is very useful to have when you buy Tear of the Goddess. 1% of your max mana being added to your hp regen per 5 sec is a massive advantage in the lane and often overlooked.

Lastly while we discuss masteries, some might want to know why I haven't gone 9/0/21 for masteries? 2 Reasons, 1 being personal preference, and 2 being that Galio doesn't need utility the way I'm aiming to play him. The defensive masteries suit my offensive playstyle and give my risktaking less consequences.

-When you spawn I advise you purchase a Meki Pendant and 2 Health Potion
-After going back to the nexus for the FIRST time, you should at least be able to purchase Tear of the Goddess. If you're doing really well then possibly even Boots and Null-Magic Mantle as well.
- By 10-15 minutes in to the game you should at least have completed Tear of the Goddess and Mercury's Treads, as well as preferably buying some Sight Ward/ Vision Ward to keep track of your lane and STAY ALERT.

- Next is the important part... Since you want to play AP Galio, you need these 3 base items: Mercury's Treads, Archangel's Staff, and Rabadon's Deathcap.
- These items are your DAMAGE DEALERS
- If you aren't doing amazing, don't rush Rabadon's Deathcap, instead build defensive items.

- If the enemy team has Tanky Dps such as Jarvan IV or Blitzcrank or maybe even Olaf, buy a Sunfire Aegis instead of Zhonya's Hourglass because against these types of enemies 450 health and DoT (Damage over time) is more useful to your team in fights.

- If the enemy team has lots of AP then you want to build your 3 defensive slots as follow's: Force of Nature, Abyssal Mask and Zhonya's Hourglass.

-SIDE NOTE: Hold off on Archangel's Staff for a while because well, it's expensive and you don't need it until later when you've actually accumulated Mana by spamming abilites and going PEW PEW.

- All the items I have mentioned are my preferred items, but that doesn't mean you can't alter the build to fit your playstyle.

- Banshee's Veil, The enemy team has too many disables/ CC and you could never get the timing right on that darn Zhonya's Hourglass that everyone's been talking about.

- Lich Bane, You're a deadly ace with Galio and you like to crash parties with Righteous Gust and Punch people in the FACE for upwards of 600 DMG.

- Mejai's Soulstealer, You like rolling face and eating souls, nuff said.

- Morello's Evil Tome, You want a side of awesome sauce with your already prestigious plate of win (mana regen and cd reduction).

- Quicksilver Sash, You're frustrated with Infinite Duress, Nether Grasp, and Enchanted Crystal Arrow.

My PREFERRED SKILL SEQUENCE is as follows:
-Always max Resolute Smite whenever possible.
-Unless of course, you can put a point in Idol of Durand.
-Your next priority after these 2 is Righteous Gust.
-Lastly your ugly stepchild that you shun and insist on starving to death Bulwark.

The reason for the above order is so you can maximize your PEW PEW.

PEW PEW is your best friend, he is comprised of 2 parts, first being Righteous Gust and the second being Resolute Smite

In order to perform a SUPER PEW PEW, one must initiate with Righteous Gust, hopefully grazing some enemies and then speeding yourself towards them, apply Bulwark salve to your body or teammate's body (Whoever looks most like they've entered the DANGER ZONE).

Now you want to perform PEW #2. Use Resolute Smite to injure anyone in your area (preferably multiple enemies).

PEW PEW does ALOT of damage, so if the enemies are still alive, you need to perform the last part. Say it with me, PEW PEW CACHOO.

CACHOO of course being Idol of Durand. If they are out of range, just Flash towards them and hope to catch them in it's are of effect. An AP GAlIO's Idol of Durand has massive punch, and can do upwards of a 1000 magic dmg. So keep in mind that you can fit a whole enemy team inside the Idol of Durand.

My preferred Summoner spells are Teleport and Flash

Other Summoner spells people might want to use:

Ghost - Nice but Righteous Gust gives nice MS.

Exhaust - Good against enemy carries but you're Galio, you need MAP DOMINATION and superior placement.

Heal - Good early game but not so much later on.

Cleanse - Great spell but doesn't work for Ignite or Children of the Grave.

Fortify - Very useful at all stages of the game, but like I said, I'm not interested in Utility.

Clarity - See Tear of the Goddess.

GALIO is an excellent farmer and can dominate creeps throughout the whole duration of a game.

Last hit when possible and use Resolute Smite and Righteous Gust to clear waves of minions.

As for the Wraiths and Wolf Camps, you don't even need to see them, you can aim through walls with Resolute Smite and Righteous Gust in rapid succession to simply INSTA-GIB them.

Play Video

THANKS FOR READING, this has been my first guide EVER, and, I sincerely hope it was insightful and or rubbed off on you a little.

Also thanks to colbycheeze for the youtube video, go check out his channel
here: http://www.youtube.com/user/colbycheeze