Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
In this build i will not tell you how to play galio, theres plenty of other builds that already state that well. this is purely how i build him, and this works.
i take righteous gust before resolute smite because you can hit more minions/champs with the spell. so, more dmg in all.
bulwark is important to lvl this can boost your dmg, heal u and protect u! this works wonders with your ult.
this build plays great as a tank/support.
late game, you do not die (unless you do something really stupid.) from about lvl 6 you are a rockin tank, and you are an amazing support. as summoner spells i recommend at least teleport,because my runes are built manaregen. you need to be able to spam your abilities. get golem buff as often as possible. the second summoner spell could be anything, i like to get fortify (check masteries), cuz of + dmg to minions and the safeguard for when you are not there to save the towers. also nice to counter a tower dive. have fun being invicible!
ps: you can get sunfire sooner if you are against melees