Highs and lows is the name of the game, pick is draft or aram, not blind, and it happens on summoner's rift, or possibly a smaller map, that could be fun too, idk.
So basically, here's the sitch. Every champion has their own pool of abilities that makes them unique. Now, that being said they all have different cooldowns. While we have urf, reducing these cooldowns by 80% and the mana costs become null, this mode matches peoples cooldowns. At the begining of the game, 2 abilities are assigned High or Low, randomly.
Every so often, say once every minute or two, everyone's cooldown time on their abilities drops to the lowest/highest, depending on if it's a high or low, on the map for that particular ability slot, excluding passives, the mana cost staying the same as it normally would.
For example, we have a Varus, whose ability cooldowns (At 1 rank per ability are Q(20)V W(Passive ability, not affected)V, E(18)^ and R(110)^
We've got Galio, at Q(10)^, W(16)V, E(12)V, and R(180)^
And Ezreal, at Q(5.5)^, W(9)^, E(19)V, and R(120)V
Highs are denoted with a ^, Lows with a V
The first minute, their Q ability's cooldowns would be either 20, or 5.5, depending on if they have an up or a down. High Q's like Ezreal's and Varus's, would have a 20 second cd, whereas lows, like Galio, would have a 5.5 second cooldown. The second minute, it would swap, Ezreal's and Varus's Qs would have a 5.5 second cd, and Galio would be stuck with that 20 second cooldown.
The swap period I would think would be a lower amount of time than a minute, and I think that a tenacity buff might be in order.
The game mode involved a lot of thought in champion selection, due to having to think of what cooldowns you would be willing to give your opponents.
Thoughts and suggestions?