Galio is in a terrible spot following the preseason launch last week
The preseason update introduced a ton of changes, namely the brand new rune system. Behind the scenes, though, were almost 140 champions being changed all at once in order to help them adjust to the new runes.
Among those champions was Galio, and his base health and health growth were both raised to make up for the old runes going away. It appears, at least right now, that those stat buffs weren't nearly enough to compensate for runes. Galio is hemorrhaging losses in ranked play, and he's currently sitting at a 42 percent winrate for both mid and top lanes, according to League of Legends stats site OP.gg.
He's currently the worst performing champion in both roles.
This sudden downtrend in Galio's power comes only one patch after he was buffed into eternity, turning him into an extremely potent burst mage. In that patch, his AP scalings were buffed too high, and he needed a hotfix nerf to make him a little more tolerable. After that hotfix, he was still playing well, though.
So what happened in the preseason patch that turned him from a powerful mage to a terrible all-around champion? One word: Runes.
The new rune system is extremely fun and, ultimately, it was a buff for most champions. Unfortunately, Galio is not one of those champions. His high AP scalings enabled him to deal a decent chunk of damage in the early game by running AP runes in the old rune system. When that went away, Galio lost his early damage.
The only way for the old colossus to deal any damage now is by running a rune build that grants him AP, like Domination or Sorcery, but if he does that, he misses out on any resistances he could gain from the Resolve path—the path that grants you 130 health for choosing it. The old rune pages allowed Galio to run some AP and some tankiness, and now that he has to pick and choose one or the other, he is having a rough time.
Galio's strength has always been with his professional power, not his prowess in solo queue, so we may have to wait until the new pro seasons begin in January to get an accurate potrayal of how the runes affected him, but we will say this—right now, things aren't looking good.