Banning a team mate pick...

Should give that team mate a free dodge. And in order not to be exploited make it have a cap and a CD ala ARAM where you need to complete matches in SR Draft in order to charge them back.

Since the introduction of 10 bans I'm not only having problems with enemies banning my pick (yeah I'm training with Yasuo but that easily applied to many other picks) but also with my own "team mates" banning it. This usually comes with insults directed to me when I ask why they did that and then to a toxic behavior of that person in the match with me already being pissed off to either be forced to play with that person and even trying to carry them to victory or suffer from the dodge queue (which I had my share and I don't always have 15 minutes to wait before even starting a match).

That or either put a specific report for banning others team mate picks.

Edit: Don't like it? The add your feedback, I'm welcoming any improvement to this baseline idea.