Mini-games full of Nothing but EASTER EGGS.
I wish there were a way to develop some of these easter eggs into full mini-games:
Plants vs. Zombies - teams of all Sion vs team of Zyra's with objective. AVP - Rengars vs KZ in all jungle terrian. Teams completely comprise of the lore. Allies together vs rivals.
There's a lot of good backstories that I wish we could take a part of besides just 2 xtra gold on some kills (although the Rengar / KZ perks are pretty intense as is).