Let's Talk About Galio
So, Galio has, in my opinion, always been on the fringe of viability because he can function very well as a coutnerpick to midlaners, and despite his mana costs being incredibly high, give him a blue buff and he's probably fine, or buy a morellos/athenes(which should be his core anyway)
but you know what would INSTANTLY put him in the same tier as several champions who are frequently played even at the professional level?
One simple change.
Make his ultimate uninterrupt-able/make him unable to be disabled for the full duration. Now let's consider the following. The move already puts you in melee range and the biggest issue is getting into melee range in the first place, what with all the cc and slows that exist in the league. You could even tweak the numbers of galio's base stats(ie hp and movespeed) a bit, but this means that he is rewarded for being able to get into that range where he can use that move and thus he and his team can profit. Plus it would make aoe compositions SO much more viable and probably make them top tier.
Now, people like malphite, vi, nocturne, sion...they all have moves where they cannot be disabled. I'm not saying make him undamageable(much like the others still are) but make him the aoe version of these characters. Boom. Instant viability. Now, Galio is already a 'fun' champion but his numbers, especially his mana costs, are keeping him from being/seeing play and with just a small change here, he becomes a contender for one of the best champions in the league! :D