So i was looking for some Galio builds and it looked like none of them suited me so i tried to play him my own way and it worked out nicely Galio to begin with isn't that famous in the tank area he is kind of underestimated so lets begin shall we

Just typical tank runes with more magic resist for more burst ability early game ^_^

When you spawn you buy awith 2x and head to your lane you shouldn't have problems with the farming on level 4 you can pretty much 1 shot the ranged minions so try to last hit the melee ones and take the ones in the back with your handy Resolute smite spell.
On your first recall you should have enough money to buy Chalice of Harmony and Mercury Treads or atleast boots, oh yeah and don't forget those wards you will never feel sorry for buying them i don't see the point of adding them in the purchase order because you need them on all champions.
After you buy your next Negatron cloak you will most likely find yourself getting killed by AD's so thats why your next item is Chain Mail now lets just make it even better and upgrade that Negatron cloak we bought into a Banshee's Veil oh yeah and you can just laugh at that tryndamere's face with your next item which is Thornmail you are almost done you need some health regen so you buy your Force of Nature last but not least comes the Guardian Angel.

+ + = That's your nuking combo you add that extra shield in the beginning for the increased magic resist and for galio magic resist means power a.k.a ability power you can add in the end if you are going for that kill.

Your harrasing combo should look like this
+ You can use the shield too but i personally don't like to do it that way because later i find myself dying from mana starvation without that clarity.

Pros
- Awesome tank
- Strong farmer
- AoE Taunt it really lets your carries destroy their team in these few seconds
- You have a shield that lets you heal yourself from dying allies trolololol
- But seriously a shield that gives 90+ armor and magic resist
- His damage output early/mid game is really high

Cons
- Team dependent
- Cooldown Dependent
- Constantly out of mana (that's why we have clarity here)
- Ultimate with very long cooldown