Yeah nerf her!
Mercy should have 5 second cast time and rez should be on a timer, after she cast rez the timer will countdown to 10 seconds before the rez will activate, at this point you already spawned at the base so its better.
Her heals should be 25 per second becasue mercy dont need aiming she should really focus on her healing and bunnyhop.
Delete her gun so mercy mains cant do a battle
Mercy to throw games.
Valkyrie should never allow mercy to fly past 10 meters and she will randomly fly in any direction so you need to steer her skillfully
There you go guys a fun and balance hero.