You can add or increase a champion’s scaling by a very, very small amount.
( Let’s say, no more than 5 or 10%. Whatever’s reasonable. )
Which champion, which ability and why?

For example:
5% AP scaling on Yone’s W maximum health damage.
Scaling would change to 10 - 50 (+ 11 - 15% (+5% AP) target’s maximum health.)
Always found it weird that he had no AP scaling despite being the brother with the most magic damage in his kit. It would also make for some funny builds around it.

Or another example:

10% movement speed scaling on Volibear’s Q.
Scaling would be 10 - 90 (+120% bonus AD) (+10% Movement Speed)
It’s not much, but it’s probably enough for someone to have fun going predator lethality speed bear.