For a long time, I have had an idea for a special game mode as part of an short-time event.
As an ARAM-player, the single most frustrating thing about "ARAM" for me is whenever I'm playing a champion I don't know yet against a one trick pony who got lucky and got their gem by chance, rerolls or trading. It's really frustrating trying to figure out how to play Kai'Sa or Kennen against a level 7 Zed who pops you in 3 seconds over and over again unless you have every defensive tool up and your fingers sorted.
Hence I'd love to see a "silly" event game-mode, where the champions are also randomly assigned, but with a twist:
All champions, owned or unowned, are available at first.
But you **cannot** get the 10 champions you have the _highest_ mastery points for.
You also **cannot** get any champion you have mastery level 5 or higher on.
You **can** however get any of the 30 champions you have the _least_ mastery points for.
For the champions that match criterion 2 or 3, but not 4, the game simply acts the same as it does now for those you haven't unlocked and that aren't free to play either - it simply disables them for you, you cannot get them by draw, roll or trades.
The game mode grants special chests for good grades, which can be opened without any key:
S+ grades earn you a "Masterwork Starter Kit" chest: guaranteed to contain a champion shard for the champion you just played. 5% chance to contain a skin shard for that champion.
S and S- grades earn you a "Refined Starter Kit" chest: 80% chance to contain a champion shard for the champion you just played. 3% to contain a skin shard for that champion.
A+, A and A- grades earn you a "Basic Starter Kit" chest: 50% chance to contain a champion shard for the champion you just played. 1% chance to contain a skin shard for that champion.
Other than that, all chests contain a small amount of Blue Essence, and have a small chance to contain random shards like Hextech chests do. They cannot contain Gemstones though (since these "Starter Kit" chests are intended to be given away much more frequently than Hextech chests, and I do not want to influence the drop rate of Gemstones).
This game mode can be seen as a way to celebrate champion pool diversity, and it means everyone can explore champions they're not super comfortable with, and if they "find" one they are apparently good with, they are likely to be incentivized to add them to their champion pool, and have a small (but significantly higher than normal) chance to be rewarded with a skin shard for that champion, too.