[Gametype Idea] Tag Wars
First off, not the "Tag" you probably initially thought about.
Instead of choosing champion bans each player chooses a Tag (Marksman, Mage, Fighter, etc). Then the role that has the highest number of votes is the list of champions you and the opposing team can select from. If there is a tie it is randomly chosen between the ones that tied.
This ends up forming goofy team comps from one type of champion role.
I imagine Tank games are agony.
