This build is best on Summoner's Rift. It focuses on making Galio into a long-range death machine with his Resolute Smite (Q). It gives you plenty of magic resist and armor (rather than HP), allowing you to tank quite well, although it is by no means a pure tank build.

You will rely on the mana regen from your runes and Chalice. If you play with the wrong runes, you will NOT have enough mana for constant Q harass, which is the main supporting pillar this build is based on. Without constant Q harass, you don't get as many kills or as much gold/exp, both of which can be critical in getting the more expensive items in this build.

You will need to learn basic tactics for positioning your Q ability. Don't always target right on your opponent, instead you need to lead into your opponents (aim ahead/behind based on what they're going to do). ONLY harass with Q. You may do a W-Q combo, but using E is only for when you commit, because it uses too much mana and doesn't have enough damage to work.

Use your W on allies frequently, and if you both are getting attacked, use it on your ally because the healing you get and defense they get can help you both survive. Late-game, using W on an ally getting hit by minions is the best way to heal, as you should be getting over 100+ HP each time they get hit.

Pros:
-High magic damage potential at range
-Great pushing power
-High resilience to harassment and quick-but-weak attacks
-Can stay out for a VERY long time before going back to base.

Cons:
-Low damage potential without spells
-Reliant on your ability to hit with skill shots
-Lacks tremendous tanking ability (see Addendum: Super Mage-Tank)

I always say that a pure tank build is terrible on Galio, but I believe that needs a bit more explanation than just saying it. I have run into countless people online who believe that Galio is only a tank, and his ultimate is the only good thing about him. This is fundamentally wrong.

First of all, while Galio has the stats for a tank build, he doesn't have the abilities to complement it. Sure, he has a large AoE taunt ultimate, but that has an insanely long cooldown and as such will only be used a handful of times per game.

His other abilities are helped a lot more by an AP / off-tank build such as this. His Q is a long-range, high-damage, AoE damage + slow, with a low cooldown and mana cost, and a .7 AP ratio. It's probably one of the best abilities, it just has everything you could need in it!

His E has a higher cooldown and lower damage potential, but the directional speed boost and large linear AoE is good enough to make it worthwhile.

His W is the only other tanking ability, but it doesn't complement tankish stats, only supplements for the lack thereof, or boosts defenses even more. Plus, you should be using it to help out other tanks, or to keep your damage dealers alive, instead of only using it to help yourself tank. It actually helps you even more on someone else, what with the healing it gives.

In short, an ultimate with 170/150/130 second cooldown is NOT a good enough reason to go pure tank. AP off-tank is a MUCH better build for Galio, as it lets his other abilities shine while still making him durable enough to take some hits.

Magic Penetration marks allow your Q to deal maximum damage. Mana-per-5 per level seals are better than flat mana-per-5 seals at level 6+, and are necessary to pull off constant Q harass. Cooldown glyphs are the best for this build because you don't get any cooldown items until late into the game, if at all. Health quintessences give you enough extra HP to survive early game, and also help out late-game with the lack of extra HP from items.

I go for a 0-21-9 mastery build, buffing my defenses enough to survive quite a bit of punishment, and then getting the extra EXP and gold from utility. You could potentially change the 9 utility for 9 offense, focusing on AP per level and magic pen, but personally the extra EXP, Gold and Regen are key to this build, not to mention a faster Ghost spell.

I start with Meki Pendant, 1 health and 1 mana potion. On first B I build chalice to give me enough mana regen to last the game, then work on Merc treads. If the opposing team doesn't have much CC you could potentially use Ionian boots, although you're losing 28 magic resist, 14 AP, and 25 Tenacity.

After that, every other item is an aura item. Aegis is the quintessential defensive aura item, helping both you and all nearby allies by quite a lot. Abyssal scepter helps you with a lot of AP and magic resist, and lowers nearby enemies' magic resist by 40, allowing both you and all allies to deal an insane amount of extra damage.

Late game, you can build Will of the Ancients for a lot of AP and some much-needed Spell Vamp, allowing you to kill a creep wave and instantly replenish a ton of HP. I also build Frozen Heart, because its combination of high armor, extra mana and insane cooldown reduction (25%) is just awesome alone. However, with its extra aura of slowing enemy attack speed, it (combined with your other aura items) makes you the ultimate passive buff/debuff.

After you get your items, feel free to grab elixers, prioritizing blue and red over green. Add in oracle if you're facing enemies like twitch or eve, but your Q and E can hit without seeing anyway so it's not 100% necessary.

I'm debating whether it's worth selling Chalice late-game in favor of another, better item. You'd have enough mana w/ Frozen Heart to stay out for awhile, but I'm not 100% sure how the lack of regen affects this build late-game. I guess you can substitute a Guardian Angel, Rylai scepter or even a Rabadon's Death Cap if you're feeling powerful.

Get Q first, and upgrade it whenever you can. It's your focus ability, use it whenever you're sure to get at least one champion hit, and is awesome at clearing creep waves as well (combined with E or even W). Clear caster minions with Q and E, and also pop into wolf and wraith camps and use Q-E to farm easy gold and EXP whenever you pass by.

Get E at level 2, and up it whenever you can't get Q or R. It's your escape ability, but also helps you snipe creep waves in combination with Q. Use it against enemy champs early on ONLY when you're going in for the kill, as its early damage potential is quite low. Later on, you can use Q-E at any time if you're sure you will hit, because you have enough mana and regen to cast both. Prioritize Q over E when attacking, but use both when retreating. Fire E behind you, and lead in your enemies with Q. The slow combined with your speed boost should be enough to let you escape from many situations.

Get W at level 4, then only level it up after all your other skills have been leveled. The boost it gives at level 1 doesn't really improve as much as other spells, but it is very important to have at least one level in it. Buff your attacks with extra AP from magic resist, and use it on yourself or your allies right before getting hit. It may not affect much later on, but an instant def/magic resist boost can really decrease the burst damage from many champs.

Use your ult only when you can't get a kill without it, or you're going into a team fight. Its cooldown is far too long to use in every fight you get, and you should be able to kill quite well with a good few good W-Q-E combos.

I get Heal and Ghost because they give you the defensive and offensive edge you will need to escape many close calls, and even get kills you normally would've lost.

Save heal for the last minute if possible, because it gains effectiveness per level. Watch your allies, and feel free to use heal if it will help them survive a tower dive or champion burst. ONLY do this if you think they can get away. If they're surrounded and about to die, don't waste it because they won't survive anyway.

Ghost allows you to escape quite easily, so use it mostly as an escape. It combined with your E helps you escape almost any gank, especially with your Q's slow.

Early on, you will focus on last-hitting minions with your melee attacks, as it takes too much mana to use your spells to only kill minions. Later in the game, around level 7-8, you should be able to defeat at least the caster minions with a good Q-E combo. This should be used whenever possible, to farm up a good amount of gold and exp, both of which are essential to get to the later stages of this build.

Also, once you reach level 9+ or so and are not locked in your lane, farming the wraith and wolf camps is another great way to gain gold and exp. Use a W-Q-E combo to quickly blast down the entire camp. If it doesn't kill them, chances are that camp has been farmed several times, or that you're just a bit too low to kill the camps in one shot.

When you're on a 4v5 team or on a team with a jungler, this build and strategy works quite well. You just need to make a few small adjustments to the way you play.

1. Last-hits are secondary to survival when facing ranged/mage champs. Not to say that you can never get last hits, but if they're pushing you back you just need to give a little room. It's better to stay in the lane a bit longer and/or survive than it is to get 20 more gold.

2. Stay in EXP range as long as you can. Even if you're not getting last hits, you still get EXP if you stay a certain distance from the dying minions. Especially in a 2v1 situation, your level is sometimes your only advantage. If you stay about the distance you can Q or E a minion from, you should be able to get exp.

3. Harass, don't commit. You can get in a ton of damage on your opponents if you just harass well with Q, especially when they clump up along side minions. However, be very careful not to try and go for the kill, because one miss can not only lose the kill, it can kill YOU in a 2v1 situation.

This build, if done properly, is sure to net you several assists and even solo-kills as the little-known champion of Galio. With Heal and Ghost, as well as the long-range harassment from Q, you won't be in near as much risk as with other champions or builds, allowing you to get out of a TON of situations where you'd normally die.

Your Q has a very low cooldown, a very long range, and a fairly large AoE, plus it adds a decent slow onto its effect! In my opinion it is one of the best spells in the game, and with this build it can net you several hundred damage per hit, and kills minion waves instantly.

Your main gold will come from minions, but don't doubt the sheer income you get just by netting assists at every team fight. Even if you can't hit (or don't want to kill steal), you can use your W on one of your attacking allies and you still get an assist.

You may get a few deaths early on, but only a few. If you get several deaths in the first few minutes (6+ or so), you're doing something wrong. Around halfway through (maybe a bit later), when team fights start really happening, the assists should pour in. I've had several games where I go from a low K/D/A ratio such as 0/3/3, and then spike in the second half to something like 5/4/18. The numbers may be made up, but they're close to what I've seen in almost every game I use this build, and have a team that doesn't mass-feed.

The standard QQ Galio build is, in short, a heavy support/mage build with great survivability. If you want to really embrace the tanky stats that Galio has, while still getting all the bang for your buck with your spells, then definitely try this separate order instead.

Start your build with chalice, merc treads and aegis like normal. However, before getting the Abyssal Scepter, grab a Sunfire Cloak. 450 HP is a big deal when you have almost 200+ armor and magic resist.

After getting the sunfire cloak, grab your Abyssal Scepter, then go for either a Guardian Angel OR a Frozen Heart, depending on what you need. For overall tankiness, grab a guardian angel. For cooldowns and just vs basic attack champs, get frozen heart.

After that, you can sell your chalice to get Will of the Ancients, or go for frozen heart / guardian angel, whichever one you didn't get last time. Will of the Ancients will give you a great boost in AP and spell vamp, while the other one will provide you with even more armor/magic resist, though at this point their effects are minimal.

Just note that when you sell Chalice, you may run out of mana if you stay out for a really long time, constantly throwing spells at max cooldown. However, you should have enough mana and regen to last for some time without it, especially if you went for Frozen Heart.