Banning teamate champ declarations.

There's nothing wrong with banning out teammates that are intentionally trolling. Riven ADC, Caitlyn top lane, Leona mid lane, Sona support. None of these work and they aren't "breaking the meta," they're just intentionally feeding and assisting the enemy.

Best case scenario: banning their troll pick forces them to play properly. Worst case: they continue trolling.

Do you have a hover over FotM and you aren't first pick? Yeah I'll ban your champ too in that case. There is nothing wrong with that. If that isn't the case and someone is trolling... Just report them for griefing and explain what happened.

If people intentionally ban out a teamfight pick, they should also be prepared for that person to have a reaction.

I did that last night by accident. Didn't realize I was banning, only had a few seconds left and just banned the first champion I'd ban that came to mind.

No, it's not something that should be reported against. Maybe if they said in chat they did it just to prevent you from playing it.

All I want is a warning so real accidents won't happen again, or at least I won't have to hear the slap to the face excuse of it being an accident.

I just report them in the grieving section and write that they banned my pick

Sorry, if I don't like your pick or if I believe that the enemy team will take it before you do, I have every right to ban it.

It can be an accident.