Its still invalid

"Your a scaly ****" -Semibutcher
Try my build.

Your build is invalid.

This build isnt very good. For seals, you can also use armor ones. Chalice is enough. And take out Lich Bane and Zhonyas. There isnt any good use for zhonyas, as it makes you untargetable. Lich Bane is for burst champs like lux and akali. Dont take it. And you shouldnt max E first, seeing as its damage is very weak.
And there isnt much armor in this build, Maybe a Sunfire Cape. And GA

This build isnt very good. For seals, you can also use armor ones. Chalice is enough. And take out Lich Bane and Zhonyas. There isnt any good use for zhonyas, as it makes you untargetable. Lich Bane is for burst champs like lux and akali. Dont take it. And you shouldnt max E first, seeing as its damage is very weak.
And there isnt much armor in this build, Maybe a Sunfire Cape. And GA

This guide is really good, and it works. You are right that he is a very underrated champion but with the right team make up, his ultimate will be devastating to the other team. A Galio + Annie/Sona/Orianna ultimate together will be insane. Not to mention, even Karthus could just stand in there with his aura, or even Fiddle/Nunu.

Very underrated champ, but very good guide.

I didn't notice because seals are related to defensive stats

AHHH DAMMIT. I was making a guide and saw that Glyphs of warding are better than Seals of warding.

AHHH DAMMIT. I was making a guide and saw that Glyphs of warding are better than Seals of warding.

Keels- I have set this build up to give MAXIMUM MR at level 18.
Here is a breakdown of what you say:

Greater Seal of Shielding: 1.8 MR @ lvl. 18
Greater Glyph of Replenishment: .31 Mp5

I say:

Greater Glyph of Shielding: 2.7 MR @ lvl. 18
Greater Seal of CLarity: 1.17 Mp5 @ lvl. 18

Galio needs strong end game MR and Mp5 so that he doesn't need to be limited to taking clarity as a summoner's spell. Your way is just not as good in my opinion. You end up with lower MR throughout the entire game, and the Mp5 benefit of my suggested glyphs also surpasses yours by level 5. Read my runes section to see why this actually can be a good thing for Galio's early laning.

I'm saying your using runes that are both less effective, and their roles should be switched. You're using secondary runes, in the cases mentioned. You'd get more mana regen if you were using MP5 Glyphs instead of seals, and you'd be getting more MR if you were using Seals of shielding instead of glyphs of shielding. You're not messing anything up by doing what I'm saying, it's just that you're getting everything you have now but more.

overall.. good guide!

quite a solid build. but it think you need to rush lich bane faster than guardian angel. Don't take this as a harsh comment. I'm just telling you that people usually get Guardian Angel as a last resort. Lich bane on the other hand have wat galio needs, MS, Magic Resist, MP and AP.