Hello, This is SalaHyena, the Non-lvl30-Build writer. I made this build so others can see how I play my Galio as Tank that has AP, or APT(ank). As you can see, I build no runes, as I don't bother with buying them until I am lvl30 and go to ranked. But, If I must recommend something, it's Mana Regen runes. With Mana regen, Galio can push 1vs2 easily against some champions( Excluding Soraka etc). But I advise to go Bot lane with AD-carry, if there are no other supports.

Ahh, the masteries. The one thing I have made my own, and are about to change soon. The reason why I chose this setup is because Galio has Mana problems, benefits from Magic Resist and Cooldowns, and shouldn't be played with 0/21/9 as most tanks are. Reason? His Ult, although mainly used for taunt, can do some Serious damage to the whole enemy team, and Early game, this spell can kill nearly every DPS champ that is stupid enough to come too close.

The actual Sequence of items is Meki Pendant + Potions, then Chalice of Harmony (No need to leave the lane before you got 500G) Then Merc Treads, then, depending on the team composition, Either FoN or Thornmail. If the enemy team has champions with True Damage, for example Olaf, Kog'Maw, Corki, It is advised to do Warmogs first. But normally I Rush for early FoN (Or on AD heavy teams, Thornmail) Then go for Warmogs or Thornmail, depending on my money situation. But if you get your full build look like the one above, and Self-casting bulwark before Ulting, you can tank easily.

Summoner spells are Exhaust and Flash, as Flash can be used to initiate (or a getaway/Chase, but rarely for those) and Exhaust crushes the enemy carries' damage output. You can have CV if you don't like exhaust, but flash is important for W-Flash-R combo.

As you can see, I am clearly supporting my lane partner (or myself) in the early game, as the W gives me indirectly AP too. Q is first skill though, for Farming and checking bushes, and E is important to have so you can getaway or help others getaway.

Q: Farming, max this last, but get atleast two levels before maxing W.

W: Your best skill throughout the game, if you don't count ulti. Enemy Caitlyn's traps actually heal you if you self-cast Bulwark and run to them. Max this first.

E: Support and harrass skill. When the enemy has gotten used to Q's range, you shoot an E to them, that has more range than Q. Even though does low damage, the enemy still avoids this, as you get Movement Speed buff from this. the Bonus scales with Levels, so I max this skill second.

R: The Skill that wins team fights with considereable damage and Very Hard CC! Combined with Morgana Ulti and one AD carry it's autowin if you get in the middle of them.

The way I play Galio is the way I Prefer. I didn't build runes cause I don't own any (More details on my signature) If you have suggestion's, please, comment, and I shall test them.
Also, Plz vote for my first guide :)