Summoner Spells.
For those who played DawnGate before its demise, they had a summoner system that worked on levels. You'd get one at the start, second mid game, and the third late.
If we were to implement something like this, where you can essationally choose your summoners in game, it would add a whole better level of Strategic Diveristy.
"Do i want flash first, in case i get ganked, or maybe ignite so i can secure a kill?"
"Ugh another Zed. Guess i'll get exhaust first and grab flash later."
"Ha, they chose Varus. I'll get a ghost to rush him and cleanse to mess up his ult"
This would be a great addition to normal blind picks, like TB, so facing a Fizz goes from "Ugh i wish i brought exhaust " to "Alright, I'm facing a Fizz, better grab exhaust first."
How does it sound? Do we rip a great mechanic from a dead game or what!?