Full on outslaught, the goal is simply to rack up kills or stay alive where as both give you points. It could be nice to have as a rotation game mode.
Just something as random as this Note: This is just a shitty paint example
https://i.gyazo.com/14dae547a12924323e6178b5b892bc9b.png
With additional stuff of course, but sometimes it's nice to just throw away laning phase, objectives, strategy and just chill in an arena.
Edit: It's intended to be FFA
Isn't that the map for Battlerite?
It would be a total meme. Combat in this game is too shallow for that. The closest we can get to that is Ascension.
What might be interesting though is the arena but everytime you go down you have to pick a different champion. So some of the idea is to bring back counter champions which would help prevent the mode from feeling too one sided in all but the most imbalanced matchmaking. Items would probably have to be locked per champion to keep the mode from being too slow and cumbersome. And to help the balance of the mode further they can tweak the item preset or tweak the level each champion should be by 1 or 2.
Riot has said they haven't done champion switching though because of their game engine. rip
Man I don't think FFA has any place in League, given this community, it sounds VERY problematic. "report this player! team fighting!! report report!" Scary just to think about it. >.<
Remove relics from Ascension and give more points for kills and you have essentially this
