A Good Ol' Fassion Fist Fight -

{W}{R}
Instant
Remove target creature you control and target creature an opponent controls from the game.
At the end of turn flip a coin and your opponent chooses heads or tails. If your opponent wins the flip return all creatures he owns to play, if he loses the flip return all creatures you own to play.
I got this idea when I saw the cardname "Take it Outside" and this is immediately what I thought. I'll need help with wording obviously but it seems pretty fair.
Current Version:
A Good Ol' Fassion Fist Fight -
{W}{R}
Instant
Remove target creature you control and target creature an opponent controls from the game.
At the end of turn flip a coin and your opponent chooses heads or tails.
The winner of the flip may return to play all creatures that player owns that were removed by A Good Ol' Fassion Fist Fight this turn.Updated to fix abuse.