New Game Mode: Observer

So I heard tales from old league of legends before a time of replays where they would grab a 6th person who could not interfere with the game and would watch the game similar to replays but sometimes that person would accidentally interfere with the game do to bugs and sorts, well why not make it a gamemode?

So here is how it can work, a standard 5v5 but on each team there is an observer who would have global range on all their abilities and items but the damage of said abilities are reduced to 0 and they cant leave base. You might be wondering how can someone who would do no damage be useful, well since they have global range on all their abilities they would be perfect to cc as well as other things like buy a sightstone and ward around the map or any item that could help their team. I was thinking of also modifying some champions ults to make them supportive while they are an observer, an example could be his kit does not seem useful to be an observer since the only ability he would normally be able to use well would be his w but what if his ult instead of making himself unkillable he would make his entire team unkillable although with half the effectiveness so half the duration. Same with and his ult.

If this gamemode did exist who would you observe with as for me I would probably pick do to him having a decent heal, global armor could be fun, a stun and an ult that would boost his ally's ad and ap while active