, 
, reworked 
, 
, 
, 
, 
could also be included i believe, along with 
These guys would probably be the first ones to come forth and save Runeterra from iminent danger.
Other Champions could be a part of the HERO SQUAD, but i think these are the best for the job.
EDIT: 
and 
could also be included, courtesy of Inept Maverick.
I say to take Jayce off. Not because I see him as bad or anything, but because I look at him like he's "Booster Gold." He's a hero because it makes him look good. He has his reasons for what he did, and I won't say he was villainous by anymeans, but I see him more as a celebrity than a hero.
Bard would only intervene if the danger would affect more than Runeterra. We don't really know why and when he helps (or even how), but he's let catastrophes happen before without intervening. Taric would try to save Runeterra, but it's possible that his will just gets overridden by a Targonian and then he can't do anything.
But yeah, this list works.
could be there too
