Swap the ratios of two abilities from the same champ
I'll start.
's q ratio with his ult. 60% ratio for a 135% ratio. AP Shen is now a thing.
9 Comments
Swap E and R, so the execute now scales with AD and the E scales at up to 40% of enemy missing health.
Talk about Spin to Win. 
swap ult and snowball ratios .
2.6 AP every few seconds
switch r and e
now he has an aoe slow that also deals 200% ad
Lucian's 330% ap + 825% Bonus AD scaling on The Culling (R) with his Piercing light (Q) 120% Bonus AD.
Wukong Ult and Q.
Rip.
R and W. Stand in my pool and melt.
Switch 
's ultimate ratio with his Q. Hit them for 440% Total AD every few seconds while shredding their armor.
Though, it means that his ultimate pretty much exists purely for the knockup and applying Black Cleaver stacks.