Well to start this off this is my build ive always used and i tend to do alot of damage and barely take any so it is very useful in almost all situations plus i can't find a more suitable one for galio. this build i made byself if theres another out there i don't know i apologize but i bet i play way different than you

This build is very useful in teamfights especially with thornmail and 2 forces of nature for hp regen with his ultimate and especially when they have more ap characters than damage but with this you will be able to do tons of damage and be able to take alot too the more magic resist means the more spells u can take and the damage your spells do but mostly a good flash in the middle of a team fight and ulti will do your best at securing an ace. early game you really want to try to feed and get assists so you will be able to get to thormail so your ultimate really hurts them. mid game is where you really start gank tanking i mean a flash in again 2 or 3 of the enemy team and ulti for kills and when your not go to the wall beside wraiths and a good resolute righteous will take them out and get you gold fast. late game you should have build done if not you are close and will be able to tank turrets with an ally and secure lane movement if you haven't alrdy but when ur not get blue buff and continue to take wraiths out for gold to complete build. when your base to base fighting and have to rely on aces you need to be ulting the team and be taking all the damage because if ur dead and ur team gets an ace and they push into theres u will be back in time in they did not gg it and they came back to yours you need to be resoluting and gusting and defending and ulting as much as you can. well this is how i play galio i hope you like it.