This is a nice format to write to my good friend some basic ideas about how to play a Galio. It is not ment to be public and thus the poor gramer and editing. There are a lot of other well writen guides on this site and on other sites about how to play Galio, and they are all better written and probebly better for Pro Galio plays and I really suggest you to skip this guide and move to theres. This guide is only to give some ideas to my friend about how to play Galio while leveling on normal games and maybe on begginners low ELO ranked games.

Galio is a mid lane champion, that can be played at top lane too sometimes and even as a support. I know that you like casters, and that you useally play mid lane so this build is focused on a caster mid lane Galio.

One thing you need to understand about galio, is that he has a passive that let him build really cost effective build if against other mages in mid lane, and that is useally what you are going to face in there.

Galio's passive make him get 50% of his resistnce to magic converted to ability power. This does not mean you should build strictly magic resistnce items and be a magic tank, eventually Galio is still a caster and you do want AP, however his passive let you build him in a way that make him both tanky and have nice amount of AP early game very fast, and by that time of the game you should dominate any caster in the mid lane because you will be facing him with a bit less AP then he has, but with twice or tree times the magic resistnce he has. Had to that Galio's ability to farm a lane with Q-E comboes, you getting blue buff from about the 7 minute of the game ( I will try to play jungle when you go galio, and will try to get you blue's on CD)

Why flat MR runes for blue?
Its because you are going to face a caster in your lane and the flat MR runes will let you have such a huge edvantage over him early on compared to the Resistnce per level runes, that only surpass the flat runes at Level10 and by that time you should be so far ahead of your oponent because of the cost effective build I offer you.

Why armor per level on yellow?

Because you are not lickly to face pysical damage dealers untill game goes into team fights (aside from enemy jungler, however you are hard to gank because you can run away with your E and get defensive buff and some regain with W) at the time team fights are up, you are going to be l10 and at that point the armor per level outscale the flat armor. However, you can feel free to get the flat armor yellow if you are afraid of jungler ganks early on in no way I would say that they are bad call.

Why spell pen on red?
Because its the best AP damage rune you can put on red and you are playing AP eventually, even with all that tankyness.

You can play with those really, however think about it before you do, ask yourself what you actually get from going 21/9/0 , 21/0/9 , 9/21/0 or 9/0/21, how it does effect your game play throw out the game and so on. 9/9/9 + 3 build give you the best of all trees in order to win early game and it won't lag too bad at end game. However Galio can do well with almost every build and you can change it to whatever effect your play style the most.

So why that item order? Again, cost effectiveness. The moment you have 800g, push your lane back and get two Null-Magic Mentales. You will upgrade both later on so its not a waste.

At that point you are going to have about around 100 magic resistnce and thus 54 AP. Your enemy will be likly to get Dubble Doran ring so he will be siting on about 60 AP 40~ MR 160 more HP and 10 mana per 5. By this time I will be able to give you blue buff so you shouldn't have much mana problems either.

Your next item will be Negatron for the extra magic resistnce and AP and it will also be upgraded later on.

Now its time to upgrade your two Nulls. Get Chalice and Merc Boots, the Chalice will make your forget about mana, the merc boots will lower CC on you.

Now its time to get some AP, because eventually you are there to deal damage and getting all out resistnce will not only make you do pitful damage, it will also make enemy AD and Tanks lague at you while they nail you down and kill you. Get two Blasting Rods now and a Catalsit. you will want to build Rod of Ages and Abyssal scepter next. You will also want a Frozen Heart for the deffense agasint those annoying pysical dealers, and more importent for the CDR.

Why CDR? because you have 7 second CD main nuke 13 sec CD secondery nuke and they won't become faster with levels. You also have THE BEST ULTI IN GAME !!1!!1!ONEONE! and you want it to be up for as many team fights/ganks as possible. When you have Glecian Shroud and blue buff you are almost CDR capd (39%) Frozen heart and Blue buff will put you 4% over the cap, and with the Unholy Grail you will never need blue buff again.

Generaly I suggest you to play a few games vs bots to get the feel of Galio, then vs players and then try to adjust the build to your play style and gold managment

Q- your main nuke, has high base damage and okish scaling considering it is an AOE move with a slow on it.

W- make you or an ally overall more tanky, also heals you. You can use this to heal up in lane by getting minions agro and put it on yourself. (Alt+W to self cast) it also give you some AP because of the passive, but nothing to be too happy about. You get one point in it at level 3 and forget about that talent untill you are 14.

E- it deals ok damage and can be used for some major burst with Q combined. It also have a utility that new players tend to forget in the form of speeding you and your team up by a lot, can be used to engage to run or to place your R easier.

R- Probebly the strongest Ulti in game. deals very high damage to everyone cought in it, CC them for 2 sec and basicly make your team have 2-1.2 sec to blow them up, chain CC them use major aoe abilities and hit everyone with them and so on. It has a downside however- it can kill you if you are not healthy enough or tanky enough. Some champions can interupt it, like Janna with her ulti (unless she is cought in it so if you are vs janna catch her with it) Alistar can use his Ulti to brake the effect then stun you. Udyr can go bear stance and run in, his auto attack from the taunt will stun you. So generaly know what you are fightning and what they have used before you push that R, but a good R is a game braker.
you should consider to cancel it after 1-1.2 sec So people with merc trades will not be able to react too.