All Random option Summoner's Rift for team builder normal mode

Considering there is already role defined characters (whenever you wanna buy one you can filter them) it would be really cool if you could make a teambuilder mode which let you do the following:

1.- Let you pick a lane+role 2.- Then team you up with the others (regular teambuilder stuff) with a random Champion that was picked from a filtered role(assassin,marksman,etc.) 3.- let you pick your masteries and runes 4.- Have fun

Pretty please ;)