New Game Mode about items

an idea i had for a game mode is on a map like summoners rift or howling abyss, while trying to push lanes, you also race to purchase a fully built item. Example, 2 players have a needlessly large rod, but only one of them can purchase a Rabadon's Deathcap. once an item is purchased, no one else can buy it, so you're forced to build items fast while also trying out new items that no one else really purchases. Its gonna be a little hectic in theory, but i think Rito can find a way to balance the gameplay of this mode. What do you guys think? Criticism encouraged.