I'd like to suggest a game mode and see what everyone else thinks of it.
I think if you change a very simple thing in the game - allow ALL abilities to be able to hit friendly targets and do their intended effects - it would completely change the way people play the endgame and teamfights especially. I think it would be really easy to create (maybe just a matter of checking valid target boxes even) and really interesting to actually have to account for all the friendly targets when you shoot out a nuke. Just imagine how chaotic and deadly teamfights would be in a friendly fire mode!
Since the laning phase would not really be affected by the change, I think ARAM would be the best place for this mode.
Imagine amumu ultimates, kennen ultimates.. shyvana ults dragging all her own team together with the enemy, ALL THE SQUISHIES...
But also, blitzcrank pulling friendlies away from danger (while also dealing some damage to them), or enemies clicking on thresh lantern before the ally.. and many more.
What do you guys think?