Overwatch 2

Post-game cards are earned by performing several different actions during a match. A few examples could be: getting the best kill streak in the lobby, freezing the most enemies, or even destroying the most turrets. The game randomly picks four feats at the end of a game to display and for the lobby to vote for. You do not need an epic vote. As soon as your card shows up after a game, that should count as one. Do this twenty-one times and the achievement should unlock. Also, you can view progress made in your statistics.

Piggybacking off of the other guides, I honestly think Lucio is the best pick for this achievement. His healing song heals all allies around you without you needing to actively do anything other than just being near them.

Combine this with objectives like pushing the payload, where your team will be constantly taking a lot of fire from the enemy and the healing points add up, especially when using his "Amp It Up" ability to increase it's effectiveness in team battles. As long as you make sure to keep around the majority of your team, and you don't have another healer on your own team, you should definitely get the healing postgame card at the end of the game.

My suggestion for raising your chances of getting a postgame card are to play as Reinhardt. Block as much damage as possible with his shield and normally if it is over 8000 he ends up in the postgame cards (At least that's how it was for me). Bear in mind if other play are performing similar epic feats then you may need to block more damage to compete. Like Kexol's solution notes you do not need an epic vote but just to appear.

Considering some of the other achievements like winning 100 games and getting to rank 50 you should easily be able to get this while working towards those if you play with characters you're comfortable with.

There are a number of ways you could end up with a post-game card, from the most eliminations to highest killstreak to most healing.

I've used Reaper, Soldier: 76, Pharah, and Lucio to get the majority of my post-game cards (I'm currently at 20, which is why I haven't unlocked this achievement yet). Pharah's ultimate, as well as Reaper's, can rack up your amount of eliminations and raise your killstreak. Lucio can earn a post-game card for most healing. What this means is that you have to heal players the most, more than both your team and the enemy team. Soldier: 76 can get a post-game card for amount of kills with his helix rocket.

As long as you have 21 cards, the achievement should pop for you.