Mercy is the best healer in Overwatch. If your mission in life is to help others fulfill theirs, here's how to play your new favorite character.
I personally think that Mercy is the best healer in Overwatch. Lucio and Zenyatta can still do a lot of healing, but this is the one area where Mercy really excels.
And I dunno about you, but I think that's a lot of fun! I have a blast playing Support characters, especially healers. There's nothing more satisfying than keeping your teammate alive while they rip the enemy to shreds.
If being that behind-the-line hero sounds like your cup of tea, Mercy may be your gal.
Mercy has a set of wings that allows her to glide around the battlefield. She can't get around as fast as some characters, but she's definitely on the faster end.
She uses two weapons: the Caduceous Staff and Caduceous Blaster. The staff is her main weapon and allows her to buff an ally's damage or heal them with a steady stream of energy. The blaster is her only method of dealing damage. It works okay, but is akin to a backup pistol in Call of Duty.
While other Support characters can dish out decent damage and provide some support, Mercy is the opposite. She provides lots of support, but very little damage. The best place for her is usually hiding behind a tank and healing/buffing her allies without drawing attention to herself.
In addition to her abilities, remember that Mercy's staff has two different attacks. One (her R2 on PS4) heals allies, while the other (L2) boosts their damage output.
In general, the rule with Mercy is to stay back. I found that hiding behind a big tank like D.Va works well. That way you can boost the tank's healing and damage but still avoid getting shot yourself.
Here are a few more specific tips to help you master this healer:
...or you can just buff Pharrah. Rockets + damage buff = gg
Finally, realize that even though you'll never make the Play of the Game, someone who follows these Mercy tips will often end up on the leaderboard. And in Overwatch, getting top 4 out of 12 players isn't bad.