Galio is a broken champion
I'm not talking about strong or weak. The rework just made him impossible to balance. So let's get this. He's a tank right. No wait he's a burst mage. Wait no wait. He's an AP juggernaut? Honestly I have no damn clue what he is supposed to be right now because if he just builds AP tank he literally is one of the dumbest champions to fight right now.
Why? Because his base numbers are already insane because he is supposed to be a tank that's anti AP. But the way his kit is designed it essentially is a tank in general and the anti AP is tacked on at the end.
How you design anti AP champions
and old
. Why because against almost everyone except who they were supposed to be fighting they do terrible. Morgana essentially doesn't have an ability against AD champions, and old Veigar missed out on the only early game spike he got if you were AD. Galio is just kind of meh, here's a free shield you get for doing your normal damage rotation turning your entire kit into hit it all and dominate anyone except a really end game AD champion or hit non of it and do nothing.
Quite honestly Galio's theme has always been the guy that shits on mages by denying their early to mid game by just living and soaking through it even pre-rework. What he currently does is not only live through it, but he also destroys anyone who cannot out damage his over loaded kit. He has a dash that leads into a knock up that leads into a taunt that guarantees his entire kits damage. Nothing about his kit screams the anti mage kit other than hit ult and even then its kind of a really bad way to make his kit. His kit should be about galio himself countering mages not making mages essentially useless because he exists.
His magic damage shield should be based on his MR not his HP. His ult should give magic resist to those he is landing on based on his MR not an all out damage reduction for building MR. Then maybe just maybe his kit can ever hit the point where it is balanced. Because as it is currently he just builds AP and ignores MR because his kit just negates magic damage by building hp and he gets to make his entire team relatively tanky for 0 effort.
This is coming from someone who loved Galio before his rework and has yet to see him once even show a candle to how he used to be and sees him constantly in the patch notes because Riot has no idea how to balance this champion.